<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/drivers/soundwire/bus_type.c, branch v6.4.1</title>
<subtitle>Clone of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git</subtitle>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/'/>
<entry>
<title>Merge tag 'soundwire-6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vkoul/soundwire</title>
<updated>2023-02-25T01:29:52+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2023-02-25T01:29:52+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=595fa4e313fee3c0b69c10bbed6fffb803237306'/>
<id>595fa4e313fee3c0b69c10bbed6fffb803237306</id>
<content type='text'>
Pull soundwire updates from Vinod Koul:
 "This is a small update which features a bit of core changes and driver
  updates in Intel and cadence driver.

  Core:

   - sdw_transfer_defer() API change to drop an argument

   - Reset page address rework

   - Export sdw_nwrite_no_pm and sdw_nread_no_pm APIs

  Drivers:

   - Cadence and related intel driver updates for FIFO handling and low
     level msg transfers"

* tag 'soundwire-6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vkoul/soundwire:
  soundwire: cadence: further simplify low-level xfer_msg_defer() callback
  soundwire: cadence: use directly bus sdw_defer structure
  soundwire: bus: remove sdw_defer argument in sdw_transfer_defer()
  soundwire: stream: use consistent pattern for freeing buffers
  soundwire: bus: Remove unused reset_page_addr() callback
  soundwire: bus: Don't zero page registers after every transaction
  soundwire: bus_type: Avoid lockdep assert in sdw_drv_probe()
  soundwire: stream: Move remaining register accesses over to no_pm
  soundwire: debugfs: Switch to sdw_read_no_pm
  soundwire: Provide build stubs for common functions
  soundwire: bus: export sdw_nwrite_no_pm and sdw_nread_no_pm functions
  soundwire: cadence: remove unused sdw_cdns_master_ops declaration
  soundwire: enable optional clock registers for SoundWire 1.2 devices
  ASoC/soundwire: remove is_sdca boolean property
  soundwire: cadence: Drain the RX FIFO after an IO timeout
  soundwire: cadence: Remove wasted space in response_buf
  soundwire: cadence: Don't overflow the command FIFOs
  soundwire: intel: remove DAI startup/shutdown
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull soundwire updates from Vinod Koul:
 "This is a small update which features a bit of core changes and driver
  updates in Intel and cadence driver.

  Core:

   - sdw_transfer_defer() API change to drop an argument

   - Reset page address rework

   - Export sdw_nwrite_no_pm and sdw_nread_no_pm APIs

  Drivers:

   - Cadence and related intel driver updates for FIFO handling and low
     level msg transfers"

* tag 'soundwire-6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vkoul/soundwire:
  soundwire: cadence: further simplify low-level xfer_msg_defer() callback
  soundwire: cadence: use directly bus sdw_defer structure
  soundwire: bus: remove sdw_defer argument in sdw_transfer_defer()
  soundwire: stream: use consistent pattern for freeing buffers
  soundwire: bus: Remove unused reset_page_addr() callback
  soundwire: bus: Don't zero page registers after every transaction
  soundwire: bus_type: Avoid lockdep assert in sdw_drv_probe()
  soundwire: stream: Move remaining register accesses over to no_pm
  soundwire: debugfs: Switch to sdw_read_no_pm
  soundwire: Provide build stubs for common functions
  soundwire: bus: export sdw_nwrite_no_pm and sdw_nread_no_pm functions
  soundwire: cadence: remove unused sdw_cdns_master_ops declaration
  soundwire: enable optional clock registers for SoundWire 1.2 devices
  ASoC/soundwire: remove is_sdca boolean property
  soundwire: cadence: Drain the RX FIFO after an IO timeout
  soundwire: cadence: Remove wasted space in response_buf
  soundwire: cadence: Don't overflow the command FIFOs
  soundwire: intel: remove DAI startup/shutdown
</pre>
</div>
</content>
</entry>
<entry>
<title>soundwire: bus_type: Avoid lockdep assert in sdw_drv_probe()</title>
<updated>2023-01-31T12:03:11+00:00</updated>
<author>
<name>Richard Fitzgerald</name>
<email>rf@opensource.cirrus.com</email>
</author>
<published>2023-01-23T17:25:20+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=3dca1f89ae3455963d7b53245ecf298ea9bae857'/>
<id>3dca1f89ae3455963d7b53245ecf298ea9bae857</id>
<content type='text'>
Don't hold sdw_dev_lock while calling the peripheral driver
probe() and remove() callbacks.

Holding sdw_dev_lock around the probe() and remove() calls causes
a theoretical mutex inversion which lockdep will assert on.

During probe() the sdw_dev_lock mutex is taken first and then
ASoC/ALSA locks are taken by the probe() implementation.

During normal operation ASoC can take its locks and then trigger
a runtime resume of the component. The SoundWire resume will then
take sdw_dev_lock. This is the reverse order compared to probe().

It's not necessary to hold sdw_dev_lock when calling the probe()
and remove(), it is only used to prevent the bus core calling the
driver callbacks if there isn't a driver or the driver is removing.

All calls to the driver callbacks are guarded by the 'probed' flag.
So if sdw_dev_lock is held while setting and clearing the 'probed'
flag this is sufficient to guarantee the safety of callback
functions.

Removing the mutex from around the call to probe() means that it
is now possible for a bus event (PING response) to be handled in
parallel with the probe(). But sdw_bus_probe() already has
handling for this by calling the device update_status() after
the probe() has completed.

Example lockdep assert:
[   46.098514] ======================================================
[   46.104736] WARNING: possible circular locking dependency detected
[   46.110961] 6.1.0-rc4-jamerson #1 Tainted: G            E
[   46.116842] ------------------------------------------------------
[   46.123063] mpg123/1130 is trying to acquire lock:
[   46.127883] ffff8b445031fb80 (&amp;slave-&gt;sdw_dev_lock){+.+.}-{3:3}, at: sdw_update_slave_status+0x26/0x70
[   46.137225]
               but task is already holding lock:
[   46.143074] ffffffffc1455310 (&amp;card-&gt;pcm_mutex){+.+.}-{3:3}, at: dpcm_fe_dai_open+0x49/0x830
[   46.151536]
               which lock already depends on the new lock.[   46.159732]
               the existing dependency chain (in reverse order) is:
[   46.167231]
               -&gt; #4 (&amp;card-&gt;pcm_mutex){+.+.}-{3:3}:
[   46.173428]        __mutex_lock+0x94/0x920
[   46.177542]        snd_soc_dpcm_runtime_update+0x2e/0x100
[   46.182958]        snd_soc_dapm_put_enum_double+0x1c2/0x200
[   46.188548]        snd_ctl_elem_write+0x10c/0x1d0
[   46.193268]        snd_ctl_ioctl+0x126/0x850
[   46.197556]        __x64_sys_ioctl+0x87/0xc0
[   46.201845]        do_syscall_64+0x38/0x90
[   46.205959]        entry_SYSCALL_64_after_hwframe+0x63/0xcd
[   46.211553]
               -&gt; #3 (&amp;card-&gt;controls_rwsem){++++}-{3:3}:
[   46.218188]        down_write+0x2b/0xd0
[   46.222038]        snd_ctl_add_replace+0x39/0xb0
[   46.226672]        snd_soc_add_controls+0x53/0x80
[   46.231393]        soc_probe_component+0x1e4/0x2a0
[   46.236202]        snd_soc_bind_card+0x51a/0xc80
[   46.240836]        devm_snd_soc_register_card+0x43/0x90
[   46.246079]        mc_probe+0x982/0xfe0 [snd_soc_sof_sdw]
[   46.251500]        platform_probe+0x3c/0xa0
[   46.255700]        really_probe+0xde/0x390
[   46.259814]        __driver_probe_device+0x78/0x180
[   46.264710]        driver_probe_device+0x1e/0x90
[   46.269347]        __driver_attach+0x9f/0x1f0
[   46.273721]        bus_for_each_dev+0x78/0xc0
[   46.278098]        bus_add_driver+0x1ac/0x200
[   46.282473]        driver_register+0x8f/0xf0
[   46.286759]        do_one_initcall+0x58/0x310
[   46.291136]        do_init_module+0x4c/0x1f0
[   46.295422]        __do_sys_finit_module+0xb4/0x130
[   46.300321]        do_syscall_64+0x38/0x90
[   46.304434]        entry_SYSCALL_64_after_hwframe+0x63/0xcd
[   46.310027]
               -&gt; #2 (&amp;card-&gt;mutex){+.+.}-{3:3}:
[   46.315883]        __mutex_lock+0x94/0x920
[   46.320000]        snd_soc_bind_card+0x3e/0xc80
[   46.324551]        devm_snd_soc_register_card+0x43/0x90
[   46.329798]        mc_probe+0x982/0xfe0 [snd_soc_sof_sdw]
[   46.335219]        platform_probe+0x3c/0xa0
[   46.339420]        really_probe+0xde/0x390
[   46.343532]        __driver_probe_device+0x78/0x180
[   46.348430]        driver_probe_device+0x1e/0x90
[   46.353065]        __driver_attach+0x9f/0x1f0
[   46.357437]        bus_for_each_dev+0x78/0xc0
[   46.361812]        bus_add_driver+0x1ac/0x200
[   46.366716]        driver_register+0x8f/0xf0
[   46.371528]        do_one_initcall+0x58/0x310
[   46.376424]        do_init_module+0x4c/0x1f0
[   46.381239]        __do_sys_finit_module+0xb4/0x130
[   46.386665]        do_syscall_64+0x38/0x90
[   46.391299]        entry_SYSCALL_64_after_hwframe+0x63/0xcd
[   46.397416]
               -&gt; #1 (client_mutex){+.+.}-{3:3}:
[   46.404307]        __mutex_lock+0x94/0x920
[   46.408941]        snd_soc_add_component+0x24/0x2c0
[   46.414345]        devm_snd_soc_register_component+0x54/0xa0
[   46.420522]        cs35l56_common_probe+0x280/0x370 [snd_soc_cs35l56]
[   46.427487]        cs35l56_sdw_probe+0xf4/0x170 [snd_soc_cs35l56_sdw]
[   46.434442]        sdw_drv_probe+0x80/0x1a0
[   46.439136]        really_probe+0xde/0x390
[   46.443738]        __driver_probe_device+0x78/0x180
[   46.449120]        driver_probe_device+0x1e/0x90
[   46.454247]        __driver_attach+0x9f/0x1f0
[   46.459106]        bus_for_each_dev+0x78/0xc0
[   46.463971]        bus_add_driver+0x1ac/0x200
[   46.468825]        driver_register+0x8f/0xf0
[   46.473592]        do_one_initcall+0x58/0x310
[   46.478441]        do_init_module+0x4c/0x1f0
[   46.483202]        __do_sys_finit_module+0xb4/0x130
[   46.488572]        do_syscall_64+0x38/0x90
[   46.493158]        entry_SYSCALL_64_after_hwframe+0x63/0xcd
[   46.499229]
               -&gt; #0 (&amp;slave-&gt;sdw_dev_lock){+.+.}-{3:3}:
[   46.506737]        __lock_acquire+0x1121/0x1df0
[   46.511765]        lock_acquire+0xd5/0x300
[   46.516360]        __mutex_lock+0x94/0x920
[   46.520949]        sdw_update_slave_status+0x26/0x70
[   46.526409]        sdw_clear_slave_status+0xd8/0xe0
[   46.531783]        intel_resume_runtime+0x139/0x2a0
[   46.537155]        __rpm_callback+0x41/0x120
[   46.541919]        rpm_callback+0x5d/0x70
[   46.546422]        rpm_resume+0x531/0x7e0
[   46.550920]        __pm_runtime_resume+0x4a/0x80
[   46.556024]        snd_soc_pcm_component_pm_runtime_get+0x2f/0xc0
[   46.562611]        __soc_pcm_open+0x62/0x520
[   46.567375]        dpcm_be_dai_startup+0x116/0x210
[   46.572661]        dpcm_fe_dai_open+0xf7/0x830
[   46.577597]        snd_pcm_open_substream+0x54a/0x8b0
[   46.583145]        snd_pcm_open.part.0+0xdc/0x200
[   46.588341]        snd_pcm_playback_open+0x51/0x80
[   46.593625]        chrdev_open+0xc0/0x250
[   46.598129]        do_dentry_open+0x15f/0x430
[   46.602981]        path_openat+0x75e/0xa80
[   46.607575]        do_filp_open+0xb2/0x160
[   46.612162]        do_sys_openat2+0x9a/0x160
[   46.616922]        __x64_sys_openat+0x53/0xa0
[   46.621767]        do_syscall_64+0x38/0x90
[   46.626352]        entry_SYSCALL_64_after_hwframe+0x63/0xcd
[   46.632414]
               other info that might help us debug this:[   46.641862] Chain exists of:
                 &amp;slave-&gt;sdw_dev_lock --&gt; &amp;card-&gt;controls_rwsem --&gt; &amp;card-&gt;pcm_mutex[   46.655145]  Possible unsafe locking scenario:[   46.662048]        CPU0                    CPU1
[   46.667080]        ----                    ----
[   46.672108]   lock(&amp;card-&gt;pcm_mutex);
[   46.676267]                                lock(&amp;card-&gt;controls_rwsem);
[   46.683382]                                lock(&amp;card-&gt;pcm_mutex);
[   46.690063]   lock(&amp;slave-&gt;sdw_dev_lock);
[   46.694574]
                *** DEADLOCK ***[   46.701942] 2 locks held by mpg123/1130:
[   46.706356]  #0: ffff8b4457b22b90 (&amp;pcm-&gt;open_mutex){+.+.}-{3:3}, at: snd_pcm_open.part.0+0xc9/0x200
[   46.715999]  #1: ffffffffc1455310 (&amp;card-&gt;pcm_mutex){+.+.}-{3:3}, at: dpcm_fe_dai_open+0x49/0x830
[   46.725390]
               stack backtrace:
[   46.730752] CPU: 0 PID: 1130 Comm: mpg123 Tainted: G            E      6.1.0-rc4-jamerson #1
[   46.739703] Hardware name: AAEON UP-WHL01/UP-WHL01, BIOS UPW1AM19 11/10/2020
[   46.747270] Call Trace:
[   46.750239]  &lt;TASK&gt;
[   46.752857]  dump_stack_lvl+0x56/0x73
[   46.757045]  check_noncircular+0x102/0x120
[   46.761664]  __lock_acquire+0x1121/0x1df0
[   46.766197]  lock_acquire+0xd5/0x300
[   46.770292]  ? sdw_update_slave_status+0x26/0x70
[   46.775432]  ? lock_is_held_type+0xe2/0x140
[   46.780143]  __mutex_lock+0x94/0x920
[   46.784241]  ? sdw_update_slave_status+0x26/0x70
[   46.789387]  ? find_held_lock+0x2b/0x80
[   46.793750]  ? sdw_update_slave_status+0x26/0x70
[   46.798894]  ? lock_release+0x147/0x2f0
[   46.803262]  ? lockdep_init_map_type+0x47/0x250
[   46.808315]  ? sdw_update_slave_status+0x26/0x70
[   46.813456]  sdw_update_slave_status+0x26/0x70
[   46.818422]  sdw_clear_slave_status+0xd8/0xe0
[   46.823302]  ? pm_generic_runtime_suspend+0x30/0x30
[   46.828706]  intel_resume_runtime+0x139/0x2a0
[   46.833583]  ? _raw_spin_unlock_irq+0x24/0x50
[   46.838462]  ? pm_generic_runtime_suspend+0x30/0x30
[   46.843866]  __rpm_callback+0x41/0x120
[   46.848142]  ? pm_generic_runtime_suspend+0x30/0x30
[   46.853550]  rpm_callback+0x5d/0x70
[   46.857568]  rpm_resume+0x531/0x7e0
[   46.861578]  ? _raw_spin_lock_irqsave+0x62/0x70
[   46.866634]  __pm_runtime_resume+0x4a/0x80
[   46.871258]  snd_soc_pcm_component_pm_runtime_get+0x2f/0xc0
[   46.877358]  __soc_pcm_open+0x62/0x520
[   46.881634]  ? dpcm_add_paths.isra.0+0x35d/0x4c0
[   46.886784]  dpcm_be_dai_startup+0x116/0x210
[   46.891592]  dpcm_fe_dai_open+0xf7/0x830
[   46.896046]  ? debug_mutex_init+0x33/0x50
[   46.900591]  snd_pcm_open_substream+0x54a/0x8b0
[   46.905658]  snd_pcm_open.part.0+0xdc/0x200
[   46.910376]  ? wake_up_q+0x90/0x90
[   46.914312]  snd_pcm_playback_open+0x51/0x80
[   46.919118]  chrdev_open+0xc0/0x250
[   46.923147]  ? cdev_device_add+0x90/0x90
[   46.927608]  do_dentry_open+0x15f/0x430
[   46.931976]  path_openat+0x75e/0xa80
[   46.936086]  do_filp_open+0xb2/0x160
[   46.940194]  ? lock_release+0x147/0x2f0
[   46.944563]  ? _raw_spin_unlock+0x29/0x50
[   46.949101]  do_sys_openat2+0x9a/0x160
[   46.953377]  __x64_sys_openat+0x53/0xa0
[   46.957733]  do_syscall_64+0x38/0x90
[   46.961829]  entry_SYSCALL_64_after_hwframe+0x63/0xcd
[   46.967402] RIP: 0033:0x7fa6397ccd3b
[   46.971506] Code: 25 00 00 41 00 3d 00 00 41 00 74 4b 64 8b 04 25 18 00 00 00 85 c0 75 67 44 89 e2 48 89 ee bf 9c ff ff ff b8 01 01 00 00 0f 05 &lt;48&gt; 3d 00 f0 ff ff 0f 87 91 00 00 00 48 8b 4c 24 28 64 48 33 0c 25
[   46.991413] RSP: 002b:00007fff838e8990 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
[   46.999580] RAX: ffffffffffffffda RBX: 0000000000080802 RCX: 00007fa6397ccd3b
[   47.007311] RDX: 0000000000080802 RSI: 00007fff838e8b50 RDI: 00000000ffffff9c
[   47.015047] RBP: 00007fff838e8b50 R08: 0000000000000000 R09: 0000000000000011
[   47.022787] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000080802
[   47.030539] R13: 0000000000000004 R14: 0000000000000000 R15: 00007fff838e8b50
[   47.038289]  &lt;/TASK&gt;

Signed-off-by: Richard Fitzgerald &lt;rf@opensource.cirrus.com&gt;
Reviewed-by: Pierre-Louis Bossart &lt;pierre-louis.bossart@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20230123172520.339367-1-rf@opensource.cirrus.com
Signed-off-by: Vinod Koul &lt;vkoul@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Don't hold sdw_dev_lock while calling the peripheral driver
probe() and remove() callbacks.

Holding sdw_dev_lock around the probe() and remove() calls causes
a theoretical mutex inversion which lockdep will assert on.

During probe() the sdw_dev_lock mutex is taken first and then
ASoC/ALSA locks are taken by the probe() implementation.

During normal operation ASoC can take its locks and then trigger
a runtime resume of the component. The SoundWire resume will then
take sdw_dev_lock. This is the reverse order compared to probe().

It's not necessary to hold sdw_dev_lock when calling the probe()
and remove(), it is only used to prevent the bus core calling the
driver callbacks if there isn't a driver or the driver is removing.

All calls to the driver callbacks are guarded by the 'probed' flag.
So if sdw_dev_lock is held while setting and clearing the 'probed'
flag this is sufficient to guarantee the safety of callback
functions.

Removing the mutex from around the call to probe() means that it
is now possible for a bus event (PING response) to be handled in
parallel with the probe(). But sdw_bus_probe() already has
handling for this by calling the device update_status() after
the probe() has completed.

Example lockdep assert:
[   46.098514] ======================================================
[   46.104736] WARNING: possible circular locking dependency detected
[   46.110961] 6.1.0-rc4-jamerson #1 Tainted: G            E
[   46.116842] ------------------------------------------------------
[   46.123063] mpg123/1130 is trying to acquire lock:
[   46.127883] ffff8b445031fb80 (&amp;slave-&gt;sdw_dev_lock){+.+.}-{3:3}, at: sdw_update_slave_status+0x26/0x70
[   46.137225]
               but task is already holding lock:
[   46.143074] ffffffffc1455310 (&amp;card-&gt;pcm_mutex){+.+.}-{3:3}, at: dpcm_fe_dai_open+0x49/0x830
[   46.151536]
               which lock already depends on the new lock.[   46.159732]
               the existing dependency chain (in reverse order) is:
[   46.167231]
               -&gt; #4 (&amp;card-&gt;pcm_mutex){+.+.}-{3:3}:
[   46.173428]        __mutex_lock+0x94/0x920
[   46.177542]        snd_soc_dpcm_runtime_update+0x2e/0x100
[   46.182958]        snd_soc_dapm_put_enum_double+0x1c2/0x200
[   46.188548]        snd_ctl_elem_write+0x10c/0x1d0
[   46.193268]        snd_ctl_ioctl+0x126/0x850
[   46.197556]        __x64_sys_ioctl+0x87/0xc0
[   46.201845]        do_syscall_64+0x38/0x90
[   46.205959]        entry_SYSCALL_64_after_hwframe+0x63/0xcd
[   46.211553]
               -&gt; #3 (&amp;card-&gt;controls_rwsem){++++}-{3:3}:
[   46.218188]        down_write+0x2b/0xd0
[   46.222038]        snd_ctl_add_replace+0x39/0xb0
[   46.226672]        snd_soc_add_controls+0x53/0x80
[   46.231393]        soc_probe_component+0x1e4/0x2a0
[   46.236202]        snd_soc_bind_card+0x51a/0xc80
[   46.240836]        devm_snd_soc_register_card+0x43/0x90
[   46.246079]        mc_probe+0x982/0xfe0 [snd_soc_sof_sdw]
[   46.251500]        platform_probe+0x3c/0xa0
[   46.255700]        really_probe+0xde/0x390
[   46.259814]        __driver_probe_device+0x78/0x180
[   46.264710]        driver_probe_device+0x1e/0x90
[   46.269347]        __driver_attach+0x9f/0x1f0
[   46.273721]        bus_for_each_dev+0x78/0xc0
[   46.278098]        bus_add_driver+0x1ac/0x200
[   46.282473]        driver_register+0x8f/0xf0
[   46.286759]        do_one_initcall+0x58/0x310
[   46.291136]        do_init_module+0x4c/0x1f0
[   46.295422]        __do_sys_finit_module+0xb4/0x130
[   46.300321]        do_syscall_64+0x38/0x90
[   46.304434]        entry_SYSCALL_64_after_hwframe+0x63/0xcd
[   46.310027]
               -&gt; #2 (&amp;card-&gt;mutex){+.+.}-{3:3}:
[   46.315883]        __mutex_lock+0x94/0x920
[   46.320000]        snd_soc_bind_card+0x3e/0xc80
[   46.324551]        devm_snd_soc_register_card+0x43/0x90
[   46.329798]        mc_probe+0x982/0xfe0 [snd_soc_sof_sdw]
[   46.335219]        platform_probe+0x3c/0xa0
[   46.339420]        really_probe+0xde/0x390
[   46.343532]        __driver_probe_device+0x78/0x180
[   46.348430]        driver_probe_device+0x1e/0x90
[   46.353065]        __driver_attach+0x9f/0x1f0
[   46.357437]        bus_for_each_dev+0x78/0xc0
[   46.361812]        bus_add_driver+0x1ac/0x200
[   46.366716]        driver_register+0x8f/0xf0
[   46.371528]        do_one_initcall+0x58/0x310
[   46.376424]        do_init_module+0x4c/0x1f0
[   46.381239]        __do_sys_finit_module+0xb4/0x130
[   46.386665]        do_syscall_64+0x38/0x90
[   46.391299]        entry_SYSCALL_64_after_hwframe+0x63/0xcd
[   46.397416]
               -&gt; #1 (client_mutex){+.+.}-{3:3}:
[   46.404307]        __mutex_lock+0x94/0x920
[   46.408941]        snd_soc_add_component+0x24/0x2c0
[   46.414345]        devm_snd_soc_register_component+0x54/0xa0
[   46.420522]        cs35l56_common_probe+0x280/0x370 [snd_soc_cs35l56]
[   46.427487]        cs35l56_sdw_probe+0xf4/0x170 [snd_soc_cs35l56_sdw]
[   46.434442]        sdw_drv_probe+0x80/0x1a0
[   46.439136]        really_probe+0xde/0x390
[   46.443738]        __driver_probe_device+0x78/0x180
[   46.449120]        driver_probe_device+0x1e/0x90
[   46.454247]        __driver_attach+0x9f/0x1f0
[   46.459106]        bus_for_each_dev+0x78/0xc0
[   46.463971]        bus_add_driver+0x1ac/0x200
[   46.468825]        driver_register+0x8f/0xf0
[   46.473592]        do_one_initcall+0x58/0x310
[   46.478441]        do_init_module+0x4c/0x1f0
[   46.483202]        __do_sys_finit_module+0xb4/0x130
[   46.488572]        do_syscall_64+0x38/0x90
[   46.493158]        entry_SYSCALL_64_after_hwframe+0x63/0xcd
[   46.499229]
               -&gt; #0 (&amp;slave-&gt;sdw_dev_lock){+.+.}-{3:3}:
[   46.506737]        __lock_acquire+0x1121/0x1df0
[   46.511765]        lock_acquire+0xd5/0x300
[   46.516360]        __mutex_lock+0x94/0x920
[   46.520949]        sdw_update_slave_status+0x26/0x70
[   46.526409]        sdw_clear_slave_status+0xd8/0xe0
[   46.531783]        intel_resume_runtime+0x139/0x2a0
[   46.537155]        __rpm_callback+0x41/0x120
[   46.541919]        rpm_callback+0x5d/0x70
[   46.546422]        rpm_resume+0x531/0x7e0
[   46.550920]        __pm_runtime_resume+0x4a/0x80
[   46.556024]        snd_soc_pcm_component_pm_runtime_get+0x2f/0xc0
[   46.562611]        __soc_pcm_open+0x62/0x520
[   46.567375]        dpcm_be_dai_startup+0x116/0x210
[   46.572661]        dpcm_fe_dai_open+0xf7/0x830
[   46.577597]        snd_pcm_open_substream+0x54a/0x8b0
[   46.583145]        snd_pcm_open.part.0+0xdc/0x200
[   46.588341]        snd_pcm_playback_open+0x51/0x80
[   46.593625]        chrdev_open+0xc0/0x250
[   46.598129]        do_dentry_open+0x15f/0x430
[   46.602981]        path_openat+0x75e/0xa80
[   46.607575]        do_filp_open+0xb2/0x160
[   46.612162]        do_sys_openat2+0x9a/0x160
[   46.616922]        __x64_sys_openat+0x53/0xa0
[   46.621767]        do_syscall_64+0x38/0x90
[   46.626352]        entry_SYSCALL_64_after_hwframe+0x63/0xcd
[   46.632414]
               other info that might help us debug this:[   46.641862] Chain exists of:
                 &amp;slave-&gt;sdw_dev_lock --&gt; &amp;card-&gt;controls_rwsem --&gt; &amp;card-&gt;pcm_mutex[   46.655145]  Possible unsafe locking scenario:[   46.662048]        CPU0                    CPU1
[   46.667080]        ----                    ----
[   46.672108]   lock(&amp;card-&gt;pcm_mutex);
[   46.676267]                                lock(&amp;card-&gt;controls_rwsem);
[   46.683382]                                lock(&amp;card-&gt;pcm_mutex);
[   46.690063]   lock(&amp;slave-&gt;sdw_dev_lock);
[   46.694574]
                *** DEADLOCK ***[   46.701942] 2 locks held by mpg123/1130:
[   46.706356]  #0: ffff8b4457b22b90 (&amp;pcm-&gt;open_mutex){+.+.}-{3:3}, at: snd_pcm_open.part.0+0xc9/0x200
[   46.715999]  #1: ffffffffc1455310 (&amp;card-&gt;pcm_mutex){+.+.}-{3:3}, at: dpcm_fe_dai_open+0x49/0x830
[   46.725390]
               stack backtrace:
[   46.730752] CPU: 0 PID: 1130 Comm: mpg123 Tainted: G            E      6.1.0-rc4-jamerson #1
[   46.739703] Hardware name: AAEON UP-WHL01/UP-WHL01, BIOS UPW1AM19 11/10/2020
[   46.747270] Call Trace:
[   46.750239]  &lt;TASK&gt;
[   46.752857]  dump_stack_lvl+0x56/0x73
[   46.757045]  check_noncircular+0x102/0x120
[   46.761664]  __lock_acquire+0x1121/0x1df0
[   46.766197]  lock_acquire+0xd5/0x300
[   46.770292]  ? sdw_update_slave_status+0x26/0x70
[   46.775432]  ? lock_is_held_type+0xe2/0x140
[   46.780143]  __mutex_lock+0x94/0x920
[   46.784241]  ? sdw_update_slave_status+0x26/0x70
[   46.789387]  ? find_held_lock+0x2b/0x80
[   46.793750]  ? sdw_update_slave_status+0x26/0x70
[   46.798894]  ? lock_release+0x147/0x2f0
[   46.803262]  ? lockdep_init_map_type+0x47/0x250
[   46.808315]  ? sdw_update_slave_status+0x26/0x70
[   46.813456]  sdw_update_slave_status+0x26/0x70
[   46.818422]  sdw_clear_slave_status+0xd8/0xe0
[   46.823302]  ? pm_generic_runtime_suspend+0x30/0x30
[   46.828706]  intel_resume_runtime+0x139/0x2a0
[   46.833583]  ? _raw_spin_unlock_irq+0x24/0x50
[   46.838462]  ? pm_generic_runtime_suspend+0x30/0x30
[   46.843866]  __rpm_callback+0x41/0x120
[   46.848142]  ? pm_generic_runtime_suspend+0x30/0x30
[   46.853550]  rpm_callback+0x5d/0x70
[   46.857568]  rpm_resume+0x531/0x7e0
[   46.861578]  ? _raw_spin_lock_irqsave+0x62/0x70
[   46.866634]  __pm_runtime_resume+0x4a/0x80
[   46.871258]  snd_soc_pcm_component_pm_runtime_get+0x2f/0xc0
[   46.877358]  __soc_pcm_open+0x62/0x520
[   46.881634]  ? dpcm_add_paths.isra.0+0x35d/0x4c0
[   46.886784]  dpcm_be_dai_startup+0x116/0x210
[   46.891592]  dpcm_fe_dai_open+0xf7/0x830
[   46.896046]  ? debug_mutex_init+0x33/0x50
[   46.900591]  snd_pcm_open_substream+0x54a/0x8b0
[   46.905658]  snd_pcm_open.part.0+0xdc/0x200
[   46.910376]  ? wake_up_q+0x90/0x90
[   46.914312]  snd_pcm_playback_open+0x51/0x80
[   46.919118]  chrdev_open+0xc0/0x250
[   46.923147]  ? cdev_device_add+0x90/0x90
[   46.927608]  do_dentry_open+0x15f/0x430
[   46.931976]  path_openat+0x75e/0xa80
[   46.936086]  do_filp_open+0xb2/0x160
[   46.940194]  ? lock_release+0x147/0x2f0
[   46.944563]  ? _raw_spin_unlock+0x29/0x50
[   46.949101]  do_sys_openat2+0x9a/0x160
[   46.953377]  __x64_sys_openat+0x53/0xa0
[   46.957733]  do_syscall_64+0x38/0x90
[   46.961829]  entry_SYSCALL_64_after_hwframe+0x63/0xcd
[   46.967402] RIP: 0033:0x7fa6397ccd3b
[   46.971506] Code: 25 00 00 41 00 3d 00 00 41 00 74 4b 64 8b 04 25 18 00 00 00 85 c0 75 67 44 89 e2 48 89 ee bf 9c ff ff ff b8 01 01 00 00 0f 05 &lt;48&gt; 3d 00 f0 ff ff 0f 87 91 00 00 00 48 8b 4c 24 28 64 48 33 0c 25
[   46.991413] RSP: 002b:00007fff838e8990 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
[   46.999580] RAX: ffffffffffffffda RBX: 0000000000080802 RCX: 00007fa6397ccd3b
[   47.007311] RDX: 0000000000080802 RSI: 00007fff838e8b50 RDI: 00000000ffffff9c
[   47.015047] RBP: 00007fff838e8b50 R08: 0000000000000000 R09: 0000000000000011
[   47.022787] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000080802
[   47.030539] R13: 0000000000000004 R14: 0000000000000000 R15: 00007fff838e8b50
[   47.038289]  &lt;/TASK&gt;

Signed-off-by: Richard Fitzgerald &lt;rf@opensource.cirrus.com&gt;
Reviewed-by: Pierre-Louis Bossart &lt;pierre-louis.bossart@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20230123172520.339367-1-rf@opensource.cirrus.com
Signed-off-by: Vinod Koul &lt;vkoul@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>driver core: make struct device_type.uevent() take a const *</title>
<updated>2023-01-27T12:45:36+00:00</updated>
<author>
<name>Greg Kroah-Hartman</name>
<email>gregkh@linuxfoundation.org</email>
</author>
<published>2023-01-11T11:30:07+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=162736b0d71a9630f7c99dda7cefd5600fa03d69'/>
<id>162736b0d71a9630f7c99dda7cefd5600fa03d69</id>
<content type='text'>
The uevent() callback in struct device_type should not be modifying the
device that is passed into it, so mark it as a const * and propagate the
function signature changes out into all relevant subsystems that use
this callback.

Cc: Alan Stern &lt;stern@rowland.harvard.edu&gt;
Cc: Andreas Noever &lt;andreas.noever@gmail.com&gt;
Cc: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Cc: Bard Liao &lt;yung-chuan.liao@linux.intel.com&gt;
Cc: Chaitanya Kulkarni &lt;kch@nvidia.com&gt;
Cc: Dan Williams &lt;dan.j.williams@intel.com&gt;
Cc: Dmitry Torokhov &lt;dmitry.torokhov@gmail.com&gt;
Cc: Frank Rowand &lt;frowand.list@gmail.com&gt;
Cc: Ira Weiny &lt;ira.weiny@intel.com&gt;
Cc: Jason Gunthorpe &lt;jgg@ziepe.ca&gt;
Cc: Jens Axboe &lt;axboe@kernel.dk&gt;
Cc: Jilin Yuan &lt;yuanjilin@cdjrlc.com&gt;
Cc: Jiri Slaby &lt;jirislaby@kernel.org&gt;
Cc: Len Brown &lt;lenb@kernel.org&gt;
Cc: Mark Gross &lt;markgross@kernel.org&gt;
Cc: "Martin K. Petersen" &lt;martin.petersen@oracle.com&gt;
Cc: "Matthew Wilcox (Oracle)" &lt;willy@infradead.org&gt;
Cc: Maximilian Luz &lt;luzmaximilian@gmail.com&gt;
Cc: Michael Jamet &lt;michael.jamet@intel.com&gt;
Cc: Ming Lei &lt;ming.lei@redhat.com&gt;
Cc: Pierre-Louis Bossart &lt;pierre-louis.bossart@linux.intel.com&gt;
Cc: Rob Herring &lt;robh+dt@kernel.org&gt;
Cc: Sakari Ailus &lt;sakari.ailus@linux.intel.com&gt;
Cc: Sanyog Kale &lt;sanyog.r.kale@intel.com&gt;
Cc: Sean Young &lt;sean@mess.org&gt;
Cc: Stefan Richter &lt;stefanr@s5r6.in-berlin.de&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Won Chung &lt;wonchung@google.com&gt;
Cc: Yehezkel Bernat &lt;YehezkelShB@gmail.com&gt;
Acked-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
Acked-by: Mika Westerberg &lt;mika.westerberg@linux.intel.com&gt; # for Thunderbolt
Acked-by: Mauro Carvalho Chehab &lt;mchehab@kernel.org&gt;
Acked-by: Alexandre Belloni &lt;alexandre.belloni@bootlin.com&gt;
Acked-by: Heikki Krogerus &lt;heikki.krogerus@linux.intel.com&gt;
Acked-by: Wolfram Sang &lt;wsa@kernel.org&gt;
Acked-by: Vinod Koul &lt;vkoul@kernel.org&gt;
Acked-by: Hans de Goede &lt;hdegoede@redhat.com&gt;
Link: https://lore.kernel.org/r/20230111113018.459199-6-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The uevent() callback in struct device_type should not be modifying the
device that is passed into it, so mark it as a const * and propagate the
function signature changes out into all relevant subsystems that use
this callback.

Cc: Alan Stern &lt;stern@rowland.harvard.edu&gt;
Cc: Andreas Noever &lt;andreas.noever@gmail.com&gt;
Cc: Andy Shevchenko &lt;andriy.shevchenko@linux.intel.com&gt;
Cc: Bard Liao &lt;yung-chuan.liao@linux.intel.com&gt;
Cc: Chaitanya Kulkarni &lt;kch@nvidia.com&gt;
Cc: Dan Williams &lt;dan.j.williams@intel.com&gt;
Cc: Dmitry Torokhov &lt;dmitry.torokhov@gmail.com&gt;
Cc: Frank Rowand &lt;frowand.list@gmail.com&gt;
Cc: Ira Weiny &lt;ira.weiny@intel.com&gt;
Cc: Jason Gunthorpe &lt;jgg@ziepe.ca&gt;
Cc: Jens Axboe &lt;axboe@kernel.dk&gt;
Cc: Jilin Yuan &lt;yuanjilin@cdjrlc.com&gt;
Cc: Jiri Slaby &lt;jirislaby@kernel.org&gt;
Cc: Len Brown &lt;lenb@kernel.org&gt;
Cc: Mark Gross &lt;markgross@kernel.org&gt;
Cc: "Martin K. Petersen" &lt;martin.petersen@oracle.com&gt;
Cc: "Matthew Wilcox (Oracle)" &lt;willy@infradead.org&gt;
Cc: Maximilian Luz &lt;luzmaximilian@gmail.com&gt;
Cc: Michael Jamet &lt;michael.jamet@intel.com&gt;
Cc: Ming Lei &lt;ming.lei@redhat.com&gt;
Cc: Pierre-Louis Bossart &lt;pierre-louis.bossart@linux.intel.com&gt;
Cc: Rob Herring &lt;robh+dt@kernel.org&gt;
Cc: Sakari Ailus &lt;sakari.ailus@linux.intel.com&gt;
Cc: Sanyog Kale &lt;sanyog.r.kale@intel.com&gt;
Cc: Sean Young &lt;sean@mess.org&gt;
Cc: Stefan Richter &lt;stefanr@s5r6.in-berlin.de&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Won Chung &lt;wonchung@google.com&gt;
Cc: Yehezkel Bernat &lt;YehezkelShB@gmail.com&gt;
Acked-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
Acked-by: Mika Westerberg &lt;mika.westerberg@linux.intel.com&gt; # for Thunderbolt
Acked-by: Mauro Carvalho Chehab &lt;mchehab@kernel.org&gt;
Acked-by: Alexandre Belloni &lt;alexandre.belloni@bootlin.com&gt;
Acked-by: Heikki Krogerus &lt;heikki.krogerus@linux.intel.com&gt;
Acked-by: Wolfram Sang &lt;wsa@kernel.org&gt;
Acked-by: Vinod Koul &lt;vkoul@kernel.org&gt;
Acked-by: Hans de Goede &lt;hdegoede@redhat.com&gt;
Link: https://lore.kernel.org/r/20230111113018.459199-6-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>soundwire: revisit driver bind/unbind and callbacks</title>
<updated>2022-07-06T07:04:21+00:00</updated>
<author>
<name>Pierre-Louis Bossart</name>
<email>pierre-louis.bossart@linux.intel.com</email>
</author>
<published>2022-06-21T22:56:38+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=bd29c00edd0a5dac8b6e7332bb470cd50f92e893'/>
<id>bd29c00edd0a5dac8b6e7332bb470cd50f92e893</id>
<content type='text'>
In the SoundWire probe, we store a pointer from the driver ops into
the 'slave' structure. This can lead to kernel oopses when unbinding
codec drivers, e.g. with the following sequence to remove machine
driver and codec driver.

/sbin/modprobe -r snd_soc_sof_sdw
/sbin/modprobe -r snd_soc_rt711

The full details can be found in the BugLink below, for reference the
two following examples show different cases of driver ops/callbacks
being invoked after the driver .remove().

kernel: BUG: kernel NULL pointer dereference, address: 0000000000000150
kernel: Workqueue: events cdns_update_slave_status_work [soundwire_cadence]
kernel: RIP: 0010:mutex_lock+0x19/0x30
kernel: Call Trace:
kernel:  ? sdw_handle_slave_status+0x426/0xe00 [soundwire_bus 94ff184bf398570c3f8ff7efe9e32529f532e4ae]
kernel:  ? newidle_balance+0x26a/0x400
kernel:  ? cdns_update_slave_status_work+0x1e9/0x200 [soundwire_cadence 1bcf98eebe5ba9833cd433323769ac923c9c6f82]

kernel: BUG: unable to handle page fault for address: ffffffffc07654c8
kernel: Workqueue: pm pm_runtime_work
kernel: RIP: 0010:sdw_bus_prep_clk_stop+0x6f/0x160 [soundwire_bus]
kernel: Call Trace:
kernel:  &lt;TASK&gt;
kernel:  sdw_cdns_clock_stop+0xb5/0x1b0 [soundwire_cadence 1bcf98eebe5ba9833cd433323769ac923c9c6f82]
kernel:  intel_suspend_runtime+0x5f/0x120 [soundwire_intel aca858f7c87048d3152a4a41bb68abb9b663a1dd]
kernel:  ? dpm_sysfs_remove+0x60/0x60

This was not detected earlier in Intel tests since the tests first
remove the parent PCI device and shut down the bus. The sequence
above is a corner case which keeps the bus operational but without a
driver bound.

While trying to solve this kernel oopses, it became clear that the
existing SoundWire bus does not deal well with the unbind case.

Commit 528be501b7d4a ("soundwire: sdw_slave: add probe_complete structure and new fields")
added a 'probed' status variable and a 'probe_complete'
struct completion. This status is however not reset on remove and
likewise the 'probe complete' is not re-initialized, so the
bind/unbind/bind test cases would fail. The timeout used before the
'update_status' callback was also a bad idea in hindsight, there
should really be no timing assumption as to if and when a driver is
bound to a device.

An initial draft was based on device_lock() and device_unlock() was
tested. This proved too complicated, with deadlocks created during the
suspend-resume sequences, which also use the same device_lock/unlock()
as the bind/unbind sequences. On a CometLake device, a bad DSDT/BIOS
caused spurious resumes and the use of device_lock() caused hangs
during suspend. After multiple weeks or testing and painful
reverse-engineering of deadlocks on different devices, we looked for
alternatives that did not interfere with the device core.

A bus notifier was used successfully to keep track of DRIVER_BOUND and
DRIVER_UNBIND events. This solved the bind-unbind-bind case in tests,
but it can still be defeated with a theoretical corner case where the
memory is freed by a .remove while the callback is in use. The
notifier only helps make sure the driver callbacks are valid, but not
that the memory allocated in probe remains valid while the callbacks
are invoked.

This patch suggests the introduction of a new 'sdw_dev_lock' mutex
protecting probe/remove and all driver callbacks. Since this mutex is
'local' to SoundWire only, it does not interfere with existing locks
and does not create deadlocks. In addition, this patch removes the
'probe_complete' completion, instead we directly invoke the
'update_status' from the probe routine. That removes any sort of
timing dependency and a much better support for the device/driver
model, the driver could be bound before the bus started, or eons after
the bus started and the hardware would be properly initialized in all
cases.

BugLink: https://github.com/thesofproject/linux/issues/3531
Fixes: 56d4fe31af77 ("soundwire: Add MIPI DisCo property helpers")
Fixes: 528be501b7d4a ("soundwire: sdw_slave: add probe_complete structure and new fields")
Signed-off-by: Pierre-Louis Bossart &lt;pierre-louis.bossart@linux.intel.com&gt;
Reviewed-by: Rander Wang &lt;rander.wang@intel.com&gt;
Reviewed-by: Ranjani Sridharan &lt;ranjani.sridharan@linux.intel.com&gt;
Reviewed-by: Bard Liao &lt;yung-chuan.liao@linux.intel.com&gt;
Reviewed-by: Péter Ujfalusi &lt;peter.ujfalusi@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20220621225641.221170-2-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul &lt;vkoul@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In the SoundWire probe, we store a pointer from the driver ops into
the 'slave' structure. This can lead to kernel oopses when unbinding
codec drivers, e.g. with the following sequence to remove machine
driver and codec driver.

/sbin/modprobe -r snd_soc_sof_sdw
/sbin/modprobe -r snd_soc_rt711

The full details can be found in the BugLink below, for reference the
two following examples show different cases of driver ops/callbacks
being invoked after the driver .remove().

kernel: BUG: kernel NULL pointer dereference, address: 0000000000000150
kernel: Workqueue: events cdns_update_slave_status_work [soundwire_cadence]
kernel: RIP: 0010:mutex_lock+0x19/0x30
kernel: Call Trace:
kernel:  ? sdw_handle_slave_status+0x426/0xe00 [soundwire_bus 94ff184bf398570c3f8ff7efe9e32529f532e4ae]
kernel:  ? newidle_balance+0x26a/0x400
kernel:  ? cdns_update_slave_status_work+0x1e9/0x200 [soundwire_cadence 1bcf98eebe5ba9833cd433323769ac923c9c6f82]

kernel: BUG: unable to handle page fault for address: ffffffffc07654c8
kernel: Workqueue: pm pm_runtime_work
kernel: RIP: 0010:sdw_bus_prep_clk_stop+0x6f/0x160 [soundwire_bus]
kernel: Call Trace:
kernel:  &lt;TASK&gt;
kernel:  sdw_cdns_clock_stop+0xb5/0x1b0 [soundwire_cadence 1bcf98eebe5ba9833cd433323769ac923c9c6f82]
kernel:  intel_suspend_runtime+0x5f/0x120 [soundwire_intel aca858f7c87048d3152a4a41bb68abb9b663a1dd]
kernel:  ? dpm_sysfs_remove+0x60/0x60

This was not detected earlier in Intel tests since the tests first
remove the parent PCI device and shut down the bus. The sequence
above is a corner case which keeps the bus operational but without a
driver bound.

While trying to solve this kernel oopses, it became clear that the
existing SoundWire bus does not deal well with the unbind case.

Commit 528be501b7d4a ("soundwire: sdw_slave: add probe_complete structure and new fields")
added a 'probed' status variable and a 'probe_complete'
struct completion. This status is however not reset on remove and
likewise the 'probe complete' is not re-initialized, so the
bind/unbind/bind test cases would fail. The timeout used before the
'update_status' callback was also a bad idea in hindsight, there
should really be no timing assumption as to if and when a driver is
bound to a device.

An initial draft was based on device_lock() and device_unlock() was
tested. This proved too complicated, with deadlocks created during the
suspend-resume sequences, which also use the same device_lock/unlock()
as the bind/unbind sequences. On a CometLake device, a bad DSDT/BIOS
caused spurious resumes and the use of device_lock() caused hangs
during suspend. After multiple weeks or testing and painful
reverse-engineering of deadlocks on different devices, we looked for
alternatives that did not interfere with the device core.

A bus notifier was used successfully to keep track of DRIVER_BOUND and
DRIVER_UNBIND events. This solved the bind-unbind-bind case in tests,
but it can still be defeated with a theoretical corner case where the
memory is freed by a .remove while the callback is in use. The
notifier only helps make sure the driver callbacks are valid, but not
that the memory allocated in probe remains valid while the callbacks
are invoked.

This patch suggests the introduction of a new 'sdw_dev_lock' mutex
protecting probe/remove and all driver callbacks. Since this mutex is
'local' to SoundWire only, it does not interfere with existing locks
and does not create deadlocks. In addition, this patch removes the
'probe_complete' completion, instead we directly invoke the
'update_status' from the probe routine. That removes any sort of
timing dependency and a much better support for the device/driver
model, the driver could be bound before the bus started, or eons after
the bus started and the hardware would be properly initialized in all
cases.

BugLink: https://github.com/thesofproject/linux/issues/3531
Fixes: 56d4fe31af77 ("soundwire: Add MIPI DisCo property helpers")
Fixes: 528be501b7d4a ("soundwire: sdw_slave: add probe_complete structure and new fields")
Signed-off-by: Pierre-Louis Bossart &lt;pierre-louis.bossart@linux.intel.com&gt;
Reviewed-by: Rander Wang &lt;rander.wang@intel.com&gt;
Reviewed-by: Ranjani Sridharan &lt;ranjani.sridharan@linux.intel.com&gt;
Reviewed-by: Bard Liao &lt;yung-chuan.liao@linux.intel.com&gt;
Reviewed-by: Péter Ujfalusi &lt;peter.ujfalusi@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20220621225641.221170-2-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul &lt;vkoul@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>soundwire: bus_type: fix remove and shutdown support</title>
<updated>2022-07-06T07:04:21+00:00</updated>
<author>
<name>Pierre-Louis Bossart</name>
<email>pierre-louis.bossart@linux.intel.com</email>
</author>
<published>2022-06-10T01:51:05+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=df6407782964dc7e35ad84230abb38f46314b245'/>
<id>df6407782964dc7e35ad84230abb38f46314b245</id>
<content type='text'>
The bus sdw_drv_remove() and sdw_drv_shutdown() helpers are used
conditionally, if the driver provides these routines.

These helpers already test if the driver provides a .remove or
.shutdown callback, so there's no harm in invoking the
sdw_drv_remove() and sdw_drv_shutdown() unconditionally.

In addition, the current code is imbalanced with
dev_pm_domain_attach() called from sdw_drv_probe(), but
dev_pm_domain_detach() called from sdw_drv_remove() only if the driver
provides a .remove callback.

Fixes: 9251345dca24b ("soundwire: Add SoundWire bus type")
Signed-off-by: Pierre-Louis Bossart &lt;pierre-louis.bossart@linux.intel.com&gt;
Reviewed-by: Rander Wang &lt;rander.wang@intel.com&gt;
Signed-off-by: Bard Liao &lt;yung-chuan.liao@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20220610015105.25987-1-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul &lt;vkoul@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The bus sdw_drv_remove() and sdw_drv_shutdown() helpers are used
conditionally, if the driver provides these routines.

These helpers already test if the driver provides a .remove or
.shutdown callback, so there's no harm in invoking the
sdw_drv_remove() and sdw_drv_shutdown() unconditionally.

In addition, the current code is imbalanced with
dev_pm_domain_attach() called from sdw_drv_probe(), but
dev_pm_domain_detach() called from sdw_drv_remove() only if the driver
provides a .remove callback.

Fixes: 9251345dca24b ("soundwire: Add SoundWire bus type")
Signed-off-by: Pierre-Louis Bossart &lt;pierre-louis.bossart@linux.intel.com&gt;
Reviewed-by: Rander Wang &lt;rander.wang@intel.com&gt;
Signed-off-by: Bard Liao &lt;yung-chuan.liao@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20220610015105.25987-1-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul &lt;vkoul@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>soundwire: bus: use correct driver name in error messages</title>
<updated>2021-03-30T06:21:42+00:00</updated>
<author>
<name>Pierre-Louis Bossart</name>
<email>pierre-louis.bossart@linux.intel.com</email>
</author>
<published>2021-03-02T09:11:12+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=0196b52b83dd7e925879ac969f1dcd543b9ea774'/>
<id>0196b52b83dd7e925879ac969f1dcd543b9ea774</id>
<content type='text'>
None of the existing codec drivers set the sdw_driver.name, but
instead set sdw_driver.driver.name.

This leads to error messages such as
[   23.935355] rt700 sdw:2:25d:700:0: Probe of (null) failed: -19

We could remove this sdw_driver.name if it doesn't have any
purpose. This patch only suggests using the proper indirection.

Signed-off-by: Pierre-Louis Bossart &lt;pierre-louis.bossart@linux.intel.com&gt;
Reviewed-by: Guennadi Liakhovetski &lt;guennadi.liakhovetski@intel.com&gt;
Reviewed-by: Kai Vehmanen &lt;kai.vehmanen@linux.intel.com&gt;
Signed-off-by: Bard Liao &lt;yung-chuan.liao@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20210302091122.13952-2-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul &lt;vkoul@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
None of the existing codec drivers set the sdw_driver.name, but
instead set sdw_driver.driver.name.

This leads to error messages such as
[   23.935355] rt700 sdw:2:25d:700:0: Probe of (null) failed: -19

We could remove this sdw_driver.name if it doesn't have any
purpose. This patch only suggests using the proper indirection.

Signed-off-by: Pierre-Louis Bossart &lt;pierre-louis.bossart@linux.intel.com&gt;
Reviewed-by: Guennadi Liakhovetski &lt;guennadi.liakhovetski@intel.com&gt;
Reviewed-by: Kai Vehmanen &lt;kai.vehmanen@linux.intel.com&gt;
Signed-off-by: Bard Liao &lt;yung-chuan.liao@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20210302091122.13952-2-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul &lt;vkoul@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>soundwire: bus: add enumerated Slave device to device list</title>
<updated>2020-09-28T05:47:40+00:00</updated>
<author>
<name>Srinivas Kandagatla</name>
<email>srinivas.kandagatla@linaro.org</email>
</author>
<published>2020-09-24T19:44:29+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=fcb9d730be1d3010e0c8fdc5aaff62836d7a942c'/>
<id>fcb9d730be1d3010e0c8fdc5aaff62836d7a942c</id>
<content type='text'>
Currently Slave devices are only added on startup, either from Device
Tree or ACPI entries. However Slave devices that are physically
present on the bus, but not described in platform firmware, will never
be added to the device list. The user/integrator can only know the
list of devices by looking a dynamic debug logs.

This patch suggests adding a Slave device even if there is no matching
DT or ACPI entry, so that we can see this in sysfs entry.

Initial code from Srinivas. Comments, fixes for ACPI probe and edits
of commit message by Pierre.

Signed-off-by: Srinivas Kandagatla &lt;srinivas.kandagatla@linaro.org&gt;
Co-developed-by: Pierre-Louis Bossart &lt;pierre-louis.bossart@linux.intel.com&gt;
Signed-off-by: Pierre-Louis Bossart &lt;pierre-louis.bossart@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20200924194430.121058-2-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul &lt;vkoul@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Currently Slave devices are only added on startup, either from Device
Tree or ACPI entries. However Slave devices that are physically
present on the bus, but not described in platform firmware, will never
be added to the device list. The user/integrator can only know the
list of devices by looking a dynamic debug logs.

This patch suggests adding a Slave device even if there is no matching
DT or ACPI entry, so that we can see this in sysfs entry.

Initial code from Srinivas. Comments, fixes for ACPI probe and edits
of commit message by Pierre.

Signed-off-by: Srinivas Kandagatla &lt;srinivas.kandagatla@linaro.org&gt;
Co-developed-by: Pierre-Louis Bossart &lt;pierre-louis.bossart@linux.intel.com&gt;
Signed-off-by: Pierre-Louis Bossart &lt;pierre-louis.bossart@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20200924194430.121058-2-pierre-louis.bossart@linux.intel.com
Signed-off-by: Vinod Koul &lt;vkoul@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>soundwire: extend SDW_SLAVE_ENTRY</title>
<updated>2020-06-30T15:56:17+00:00</updated>
<author>
<name>Pierre-Louis Bossart</name>
<email>pierre-louis.bossart@linux.intel.com</email>
</author>
<published>2020-06-08T20:54:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=b5924268d6700821fbd8afe815073b05cebaa308'/>
<id>b5924268d6700821fbd8afe815073b05cebaa308</id>
<content type='text'>
The SoundWire 1.2 specification adds new capabilities that were not
present in previous version, such as the class ID.

To enable support for class drivers, and well as drivers that address
a specific version, all fields of the sdw_device_id structure need to
be exposed. For SoundWire 1.0 and 1.1 devices, a wildcard is used so
class and version information are ignored.

Signed-off-by: Pierre-Louis Bossart &lt;pierre-louis.bossart@linux.intel.com&gt;
Reviewed-by: Rander Wang &lt;rander.wang@linux.intel.com&gt;
Reviewed-by: Guennadi Liakhovetski &lt;guennadi.liakhovetski@linux.intel.com&gt;
Signed-off-by: Bard Liao &lt;yung-chuan.liao@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20200608205436.2402-4-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul &lt;vkoul@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The SoundWire 1.2 specification adds new capabilities that were not
present in previous version, such as the class ID.

To enable support for class drivers, and well as drivers that address
a specific version, all fields of the sdw_device_id structure need to
be exposed. For SoundWire 1.0 and 1.1 devices, a wildcard is used so
class and version information are ignored.

Signed-off-by: Pierre-Louis Bossart &lt;pierre-louis.bossart@linux.intel.com&gt;
Reviewed-by: Rander Wang &lt;rander.wang@linux.intel.com&gt;
Reviewed-by: Guennadi Liakhovetski &lt;guennadi.liakhovetski@linux.intel.com&gt;
Signed-off-by: Bard Liao &lt;yung-chuan.liao@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20200608205436.2402-4-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul &lt;vkoul@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>soundwire: bus_type: convert open-coded while() to for() loop</title>
<updated>2020-06-30T15:56:17+00:00</updated>
<author>
<name>Pierre-Louis Bossart</name>
<email>pierre-louis.bossart@linux.intel.com</email>
</author>
<published>2020-06-08T20:54:34+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=ee9173db5037cf46aba47161043ec6f0e06cf9d3'/>
<id>ee9173db5037cf46aba47161043ec6f0e06cf9d3</id>
<content type='text'>
No functionality change, just more structured code.

Suggested-by: Guennadi Liakhovetski &lt;guennadi.liakhovetski@linux.intel.com&gt;
Signed-off-by: Pierre-Louis Bossart &lt;pierre-louis.bossart@linux.intel.com&gt;
Reviewed-by: Rander Wang &lt;rander.wang@linux.intel.com&gt;
Reviewed-by: Guennadi Liakhovetski &lt;guennadi.liakhovetski@linux.intel.com&gt;
Signed-off-by: Bard Liao &lt;yung-chuan.liao@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20200608205436.2402-3-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul &lt;vkoul@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
No functionality change, just more structured code.

Suggested-by: Guennadi Liakhovetski &lt;guennadi.liakhovetski@linux.intel.com&gt;
Signed-off-by: Pierre-Louis Bossart &lt;pierre-louis.bossart@linux.intel.com&gt;
Reviewed-by: Rander Wang &lt;rander.wang@linux.intel.com&gt;
Reviewed-by: Guennadi Liakhovetski &lt;guennadi.liakhovetski@linux.intel.com&gt;
Signed-off-by: Bard Liao &lt;yung-chuan.liao@linux.intel.com&gt;
Link: https://lore.kernel.org/r/20200608205436.2402-3-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul &lt;vkoul@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>soundwire: add Slave sysfs support</title>
<updated>2020-05-20T11:52:41+00:00</updated>
<author>
<name>Pierre-Louis Bossart</name>
<email>pierre-louis.bossart@linux.intel.com</email>
</author>
<published>2020-05-18T20:35:51+00:00</published>
<link rel='alternate' type='text/html' href='https://git.exis.tech/linux.git/commit/?id=bcac59029955ae57d3c660a0a1d6d4c7ae78fb49'/>
<id>bcac59029955ae57d3c660a0a1d6d4c7ae78fb49</id>
<content type='text'>
Expose MIPI DisCo Slave properties in sysfs.

For Slave properties and Data Port 0, the attributes are managed with
simple devm_ support.

A Slave Device may have more than one Data Port (DPN), and each Data
Port can be sink or source. The attributes are created dynamically
using pre-canned macros, but still use devm_ with a name attribute
group to avoid creating kobjects - as requested by GregKH. In the
_show function, we use container_of() to retrieve port number and
direction required to extract the information.

Audio modes are not supported for now. Depending on the discussions
the SoundWire Device Class, we may add it later as is or follow the
new specification.

Signed-off-by: Pierre-Louis Bossart &lt;pierre-louis.bossart@linux.intel.com&gt;
Signed-off-by: Bard Liao &lt;yung-chuan.liao@linux.intel.com&gt;
Reviewed-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Link: https://lore.kernel.org/r/20200518203551.2053-4-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul &lt;vkoul@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Expose MIPI DisCo Slave properties in sysfs.

For Slave properties and Data Port 0, the attributes are managed with
simple devm_ support.

A Slave Device may have more than one Data Port (DPN), and each Data
Port can be sink or source. The attributes are created dynamically
using pre-canned macros, but still use devm_ with a name attribute
group to avoid creating kobjects - as requested by GregKH. In the
_show function, we use container_of() to retrieve port number and
direction required to extract the information.

Audio modes are not supported for now. Depending on the discussions
the SoundWire Device Class, we may add it later as is or follow the
new specification.

Signed-off-by: Pierre-Louis Bossart &lt;pierre-louis.bossart@linux.intel.com&gt;
Signed-off-by: Bard Liao &lt;yung-chuan.liao@linux.intel.com&gt;
Reviewed-by: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Link: https://lore.kernel.org/r/20200518203551.2053-4-yung-chuan.liao@linux.intel.com
Signed-off-by: Vinod Koul &lt;vkoul@kernel.org&gt;
</pre>
</div>
</content>
</entry>
</feed>
