ACK/cmnt / APPLIED[C/Unstable]: [SRU] [Bionic/Cosmic/Unstable] [PATCH 0/1] Fix unusable NVIDIA GPU after S3

[Kai-Heng Feng]

at 15:20, Seth Forshee <seth.forshee at canonical.com> wrote:

> On Wed, Sep 19, 2018 at 11:29:15PM +0800, Kai-Heng Feng wrote:
>> BugLink: https://bugs.launchpad.net/bugs/1793338
>>
>> [Impact]
>> NVIDIA GPU on a new system we have becomes unusable after S3.
>>
>> [Test]
>> The NVIDIA GPU in question works well after applying this patch.
>>
>> [Fix]
>> Rewrite 0 to Intel PCI bridge 'Prefetchable Base Upper 32 Bits'.
>> This should be done by BIOS S3 code [1], but now the issue reappears,  
>> let's
>> do the same in Linux PCI subsystem.
>>
>> [Regression Potential]
>> Low.
>> After applying this patch I haven't noticed any change on already
>> working PCI devices.
>> Also this patch is acked by PCI and ACPI maintainers, so we can be more
>> confident.
>>
>> [1] https://bugzilla.kernel.org/show_bug.cgi?id=116851#c23
>
> I think this looks safe enough, though based on the branch it's been
> committed to and the discussion it's not entirely clear to me whether
> this patch will go upstream or something a little different. So I think
> we can apply it, but I'd ask that you keep an eye on the upstream
> discussions and send an update if upstream goes a different way.

 From what I can understand, this patch is meant to be non-intrusive, so it  
can easily be backported to older kernel releases.

This patch should land at v4.20. An more intrusive approach will land in  
later release.

For Cosmic I think we can backport the intrusive version, but for Bionic I  
think we should keep using this one.

Kai-Heng

>
> Based on the above I think this should be committed as SAUCE. With that
> done:
>
> Acked-by: Seth Forshee <seth.forshee at canonical.com>
>
> Applied to cosmic/master-next and unstable/master. Thanks!