ACK/Cmnt: [SRU] [L/M/Unstable] [PATCH 0/2] Fix numerous AER related issues

[Stefan Bader]

On 25.08.23 10:19, Kai-Heng Feng wrote:
> BugLink: https://bugs.launchpad.net/bugs/2033025
> 
> [Impact]
> Numerous issues triggered from AER/DPC services
> 
> - When AER is shared with PME, cutting the power off the device can
>    trigger AER IRQ. Since AER IRQ is shared with PME, it's treated like a
>    wakeup source, preventing the system from entering sleep.
> 
> - When system resume from S3, device can reset itself and start sending
>    PTM messages, triggering AER and reset the entire hierarchy. Since the
>    hardware/firmware starts before software, it's never soon enough to put
>    a band-aid from kernel.
> 
> - Following above one, device firmware restarts before kernel resume,
>    when DPC is triggered then the device is gone without any recovering
>    method. We really want to prevent that from happening.
> 
> [Fix]
> Disable and re-enable AER and DPC services on suspend and resume,
> respectively.  Right now the the PCI mailing list doesn't have a
> consensus which PCI state (D3hot vs D3cold) should the AER/DPC services
> should be disabled, so re-instate the old workaround for now.
> 
> [Test]
> One the workaround is applied, symptoms described above can no longer be
> observed.
> 
> [Where problems could occur]
> Theoretically there can be some "real" issues get unnoticed once AER
> gets temporarily disabled, but the benefit far outweighs the downside.
> 
> Kai-Heng Feng (2):
>    UBUNTU: SAUCE: PCI/AER: Disable AER service during suspend, again
>    UBUNTU: SAUCE: PCI/DPC: Disable DPC service during suspend, again
> 
>   drivers/pci/pcie/aer.c | 18 ++++++++++++++++
>   drivers/pci/pcie/dpc.c | 49 ++++++++++++++++++++++++++++++++----------
>   2 files changed, 56 insertions(+), 11 deletions(-)
> 

Since we used this approach before and with the arguing in the patches 
(maybe would be good to put something like that into the cover email as 
well) it sounds reasonable to add those sauce patches back to Lunar.

Acked-by: Stefan Bader <stefan.bader at canonical.com>
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