linux.git/arch/powerpc/kernel/eeh.c, branch v3.16.35

powerpc/eeh: Dump PE location code

2014-06-11T09:12:23+00:00

As Ben suggested, it's meaningful to dump PE's location code
for site engineers when hitting EEH errors. The patch introduces
function eeh_pe_loc_get() to retireve the location code from
dev-tree so that we can output it when hitting EEH errors.

If primary PE bus is root bus, the PHB's dev-node would be tried
prior to root port's dev-node. Otherwise, the upstream bridge's
dev-node of the primary PE bus will be check for the location code
directly.

Signed-off-by: Gavin Shan 
Signed-off-by: Benjamin Herrenschmidt

powerpc/eeh: Report frozen parent PE prior to child PE

2014-06-11T07:04:16+00:00

When we have the corner case of frozen parent and child PE at the
same time, we have to handle the frozen parent PE prior to the
child. Without clearning the frozen state on parent PE, the child
PE can't be recovered successfully.

The patch searches the EEH PE hierarchy tree and returns the toppest
frozen PE to be handled. It ensures the frozen parent PE will be
handled prior to child PE.

Signed-off-by: Gavin Shan 
Signed-off-by: Benjamin Herrenschmidt

powerpc/eeh: Fix build error for celleb

2014-05-20T00:54:04+00:00

Commit 7f52a526f ("powerpc/eeh: Allow to disable EEH") caused
following build error with "celleb_defconfig" as being catched
by Mikey on linux-next.

arch/powerpc/kernel/eeh.c: In function 'eeh_init_proc':
arch/powerpc/kernel/eeh.c:1173:37: error: 'powerpc_debugfs_root' \
undeclared (first use in this function)
arch/powerpc/kernel/eeh.c:1173:37: note: each undeclared identifier \
is reported only once for each function it appears in

Reported-by: Michael Neuling 
Signed-off-by: Gavin Shan 
Signed-off-by: Benjamin Herrenschmidt

powerpc/eeh: Make the delay for PE reset unified

2014-04-28T07:34:48+00:00

Basically, we have 3 types of resets to fulfil PE reset: fundamental,
hot and PHB reset. For the later 2 cases, we need PCI bus reset hold
and settlement delay as specified by PCI spec. PowerNV and pSeries
platforms are running on top of different firmware and some of the
delays have been covered by underly firmware (PowerNV).

The patch makes the delays unified to be done in backend, instead of
EEH core.

Signed-off-by: Gavin Shan 
Signed-off-by: Benjamin Herrenschmidt

powerpc/eeh: Allow to disable EEH

2014-04-28T07:34:27+00:00

The patch introduces bootarg "eeh=off" to disable EEH functinality.
Also, it creates /sys/kerenl/debug/powerpc/eeh_enable to disable
or enable EEH functionality. By default, we have the functionality
enabled.

For PowerNV platform, we will restore to have the conventional
mechanism of clearing frozen PE during PCI config access if we're
going to disable EEH functionality. Conversely, we will rely on
EEH for error recovery.

The patch also fixes the issue that we missed to cover the case
of disabled EEH functionality in function ioda_eeh_event(). Those
events driven by interrupt should be cleared to avoid endless
reporting.

Signed-off-by: Gavin Shan 
Signed-off-by: Benjamin Herrenschmidt

powerpc/eeh: Cleanup EEH subsystem variables

2014-04-28T07:34:23+00:00

There're 2 EEH subsystem variables: eeh_subsystem_enabled and
eeh_probe_mode. We needn't maintain 2 variables and we can just
have one variable and introduce different flags. The patch also
introduces additional flag EEH_FORCE_DISABLE, which will be used
to disable EEH subsystem via boot parameter ("eeh=off") in future.
Besides, the patch also introduces flag EEH_ENABLED, which is
changed to disable or enable EEH functionality on the fly through
debugfs entry in future.

With the patch applied, the creteria to check the enabled EEH
functionality is changed to:

!EEH_FORCE_DISABLED && EEH_ENABLED : Enabled
                       Other cases : Disabled

Signed-off-by: Gavin Shan 
Signed-off-by: Benjamin Herrenschmidt

powerpc/eeh: Use cached capability for log dump

2014-04-28T07:34:19+00:00

When calling into eeh_gather_pci_data() on pSeries platform, we
possiblly don't have pci_dev instance yet, but eeh_dev is always
ready. So we use cached capability from eeh_dev instead of pci_dev
for log dump there. In order to keep things unified, we also cache
PCI capability positions to eeh_dev for PowerNV as well.

Signed-off-by: Gavin Shan 
Signed-off-by: Benjamin Herrenschmidt

powerpc/eeh: Cleanup eeh_gather_pci_data()

2014-04-28T07:34:14+00:00

The patch replaces printk(KERN_WARNING ...) with pr_warn() in the
function eeh_gather_pci_data().

Signed-off-by: Gavin Shan 
Signed-off-by: Benjamin Herrenschmidt

powerpc/eeh: Avoid I/O access during PE reset

2014-04-28T07:34:10+00:00

We have suffered recrusive frozen PE a lot, which was caused
by IO accesses during the PE reset. Ben came up with the good
idea to keep frozen PE until recovery (BAR restore) gets done.
With that, IO accesses during PE reset are dropped by hardware
and wouldn't incur the recrusive frozen PE any more.

The patch implements the idea. We don't clear the frozen state
until PE reset is done completely. During the period, the EEH
core expects unfrozen state from backend to keep going. So we
have to reuse EEH_PE_RESET flag, which has been set during PE
reset, to return normal state from backend. The side effect is
we have to clear frozen state for towice (PE reset and clear it
explicitly), but that's harmless.

We have some limitations on pHyp. pHyp doesn't allow to enable
IO or DMA for unfrozen PE. So we don't enable them on unfrozen PE
in eeh_pci_enable(). We have to enable IO before grabbing logs on
pHyp. Otherwise, 0xFF's is always returned from PCI config space.
Also, we had wrong return value from eeh_pci_enable() for
EEH_OPT_THAW_DMA case. The patch fixes it too.

Signed-off-by: Gavin Shan 
Signed-off-by: Benjamin Herrenschmidt

powerpc/eeh: EEH_PE_ISOLATED not reflect HW state

2014-04-28T07:33:57+00:00

When doing PE reset, EEH_PE_ISOLATED is cleared unconditionally.
However, We should remove that if the PE reset has cleared the
frozen state successfully. Otherwise, the flag should be kept.
The patch fixes the issue.

Signed-off-by: Gavin Shan 
Signed-off-by: Benjamin Herrenschmidt