linux.git/drivers/tty/serdev, branch v6.18.21

serdev: Drop dev_pm_domain_detach() call

2025-09-06T13:48:38+00:00

Starting with commit f99508074e78 ("PM: domains: Detach on
device_unbind_cleanup()"), there is no longer a need to call
dev_pm_domain_detach() in the bus remove function. The
device_unbind_cleanup() function now handles this to avoid
invoking devres cleanup handlers while the PM domain is
powered off, which could otherwise lead to failures as
described in the above-mentioned commit.

Drop the explicit dev_pm_domain_detach() call and rely instead
on the flags passed to dev_pm_domain_attach() to power off the
domain.

Signed-off-by: Claudiu Beznea 
Reviewed-by: Ulf Hansson 
Link: https://lore.kernel.org/r/20250827101747.928265-1-claudiu.beznea.uj@bp.renesas.com
Signed-off-by: Greg Kroah-Hartman

PM: domains: Add flags to specify power on attach/detach

2025-07-07T18:41:20+00:00

Calling dev_pm_domain_attach()/dev_pm_domain_detach() in bus driver
probe/remove functions can affect system behavior when the drivers
attached to the bus use devres-managed resources. Since devres actions
may need to access device registers, calling dev_pm_domain_detach() too
early, i.e., before these actions complete, can cause failures on some
systems. One such example is Renesas RZ/G3S SoC-based platforms.

If the device clocks are managed via PM domains, invoking
dev_pm_domain_detach() in the bus driver's remove function removes the
device's clocks from the PM domain, preventing any subsequent
pm_runtime_resume*() calls from enabling those clocks.

The second argument of dev_pm_domain_attach() specifies whether the PM
domain should be powered on during attachment. Likewise, the second
argument of dev_pm_domain_detach() indicates whether the domain should be
powered off during detachment.

Upcoming changes address the issue described above (initially for the
platform bus only) by deferring the call to dev_pm_domain_detach() until
after devres_release_all() in device_unbind_cleanup(). The detach_power_off
field in struct dev_pm_info stores the detach power off info from the
second argument of dev_pm_domain_attach().

Because there are cases where the device's PM domain power-on/off behavior
must be conditional (e.g., in i2c_device_probe()), the patch introduces
PD_FLAG_ATTACH_POWER_ON and PD_FLAG_DETACH_POWER_OFF flags to be passed
to dev_pm_domain_attach().

Finally, dev_pm_domain_attach() and its users are updated to use the newly
introduced PD_FLAG_ATTACH_POWER_ON and PD_FLAG_DETACH_POWER_OFF macros.

This change is preparatory.

Signed-off-by: Claudiu Beznea 
Reviewed-by: Mathieu Poirier 
Acked-by: Wolfram Sang  # I2C
Reviewed-by: Ulf Hansson 
Link: https://patch.msgid.link/20250703112708.1621607-2-claudiu.beznea.uj@bp.renesas.com
[ rjw: Changelog adjustments ]
Signed-off-by: Rafael J. Wysocki

serdev: Refine several error or debug messages

2025-05-01T15:20:49+00:00

Refine several dev_err() and dev_dbg() messages to solve:

// hardcoded device name
dev_dbg(dev, "...dev_name_str...")

// repeated device name since dev_dbg() also prints it as prefix
dev_err(dev, "...%s...", dev_name(dev))

// not concise as dev_err(dev, "...%d...", err)
dev_err(dev, "...%pe...", ERR_PTR(err))

Signed-off-by: Zijun Hu 
Reviewed-by: Jiri Slaby 
Link: https://lore.kernel.org/r/20250425-fix_serdev-v3-1-2e4ea8261640@quicinc.com
Signed-off-by: Greg Kroah-Hartman

tty: serdev: drop serdev_controller_ops::write_room()

2025-03-20T15:00:51+00:00

In particular, serdev_device_write_room() is not called, so the whole
serdev's write_room() can go.

Signed-off-by: Jiri Slaby (SUSE) 
Cc: Rob Herring 
Link: https://lore.kernel.org/r/20250317070046.24386-17-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman

serdev: Use of_property_present()

2024-08-07T11:08:14+00:00

Use of_property_present() to test for property presence rather than
of_get_property(). This is part of a larger effort to remove callers
of of_get_property() and similar functions. of_get_property() leaks
the DT property data pointer which is a problem for dynamically
allocated nodes which may be freed.

Signed-off-by: Rob Herring (Arm) 
Link: https://lore.kernel.org/r/20240731191312.1710417-17-robh@kernel.org
Signed-off-by: Greg Kroah-Hartman

driver core: have match() callback in struct bus_type take a const *

2024-07-03T13:16:54+00:00

In the match() callback, the struct device_driver * should not be
changed, so change the function callback to be a const *.  This is one
step of many towards making the driver core safe to have struct
device_driver in read-only memory.

Because the match() callback is in all busses, all busses are modified
to handle this properly.  This does entail switching some container_of()
calls to container_of_const() to properly handle the constant *.

For some busses, like PCI and USB and HV, the const * is cast away in
the match callback as those busses do want to modify those structures at
this point in time (they have a local lock in the driver structure.)
That will have to be changed in the future if they wish to have their
struct device * in read-only-memory.

Cc: Rafael J. Wysocki 
Reviewed-by: Alex Elder 
Acked-by: Sumit Garg 
Link: https://lore.kernel.org/r/2024070136-wrongdoer-busily-01e8@gregkh
Signed-off-by: Greg Kroah-Hartman

serdev: make serdev_bus_type const

2024-02-06T14:35:38+00:00

Now that the driver core can properly handle constant struct bus_type,
move the serdev_bus_type variable to be a constant structure as well,
placing it into read-only memory which can not be modified at runtime.

Suggested-by: Greg Kroah-Hartman 
Signed-off-by: "Ricardo B. Marliere" 
Link: https://lore.kernel.org/r/20240203-bus_cleanup-tty-v1-1-86b698c82efe@marliere.net
Signed-off-by: Greg Kroah-Hartman

treewide, serdev: change receive_buf() return type to size_t

2024-01-28T02:13:53+00:00

receive_buf() is called from ttyport_receive_buf() that expects values
">= 0" from serdev_controller_receive_buf(), change its return type from
ssize_t to size_t.

The need for this clean-up was noticed while fixing a warning, see
commit 94d053942544 ("Bluetooth: btnxpuart: fix recv_buf() return value").
Changing the callback prototype to return an unsigned seems the best way
to document the API and ensure that is properly used.

GNSS drivers implementation of serdev receive_buf() callback return
directly the return value of gnss_insert_raw(). gnss_insert_raw()
returns a signed int, however this is not an issue since the value
returned is always positive, because of the kfifo_in() implementation.
gnss_insert_raw() could be changed to return also an unsigned, however
this is not implemented here as request by the GNSS maintainer Johan
Hovold.

Suggested-by: Jiri Slaby 
Link: https://lore.kernel.org/all/087be419-ec6b-47ad-851a-5e1e3ea5cfcc@kernel.org/
Signed-off-by: Francesco Dolcini 
Acked-by: Jonathan Cameron  #for-iio
Reviewed-by: Johan Hovold 
Reviewed-by: Rob Herring 
Reviewed-by: Alex Elder 
Acked-by: Maximilian Luz   # for platform/surface
Acked-by: Lee Jones 
Acked-by: Ilpo Järvinen 
Link: https://lore.kernel.org/r/20240122180551.34429-1-francesco@dolcini.it
Signed-off-by: Greg Kroah-Hartman

serdev: Remove usage of the deprecated ida_simple_xx() API

2023-12-15T13:20:06+00:00

ida_alloc() and ida_free() should be preferred to the deprecated
ida_simple_get() and ida_simple_remove().

This is less verbose.

Signed-off-by: Christophe JAILLET 
Link: https://lore.kernel.org/r/d20d3ac106bac6b7cabe39f22ad00ac86910e0a5.1702230342.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Greg Kroah-Hartman

tty: serdev: convert to u8 and size_t

2023-12-08T11:02:38+00:00

Switch character types to u8 and sizes to size_t. To conform to
characters/sizes in the rest of the tty layer.

This patch converts struct serdev_device_ops hooks and its
instantiations.

Signed-off-by: "Jiri Slaby (SUSE)" 
Cc: Rob Herring 
Acked-by: Johan Hovold 
Link: https://lore.kernel.org/r/20231206073712.17776-24-jirislaby@kernel.org
Signed-off-by: Greg Kroah-Hartman