[Intel-gfx] Potential BUG in drm/i915/execlists: Reset RING registers upon resume

[Eric Blau]

On Mon, Mar 20, 2017 at 11:13 AM, Greg Kroah-Hartman
<gregkh at linuxfoundation.org> wrote:
> On Mon, Mar 20, 2017 at 05:01:34PM +0200, Jani Nikula wrote:
>> On Tue, 14 Mar 2017, Eric Blau <eblau at eblau.com> wrote:
>> > That's funny. I have a MacBook Pro 12,1 from late 2015. Hibernate
>> > failed for me in 4.9.6 through 4.9.8 (possibly earlier as well, I do
>> > no recall) without the patch. The patch you reference fixed my problem
>> > and apparently many others based on the bug reports:
>> >
>> > https://bugs.freedesktop.org/show_bug.cgi?id=96526
>> >
>> > I applied the patch myself in 4.9.6 through 4.9.8 and hibernate works
>> > for me. I have run vanilla 4.9.9 and 4.10.1 and in both hibernate
>> > works.
>>
>> So I'm quite surprised
>>
>> commit f2a0409a08502d64fbe3990354dff5902b08d2fb
>> Author: Chris Wilson <chris at chris-wilson.co.uk>
>> Date:   Wed Sep 21 14:51:08 2016 +0100
>>
>>     drm/i915/execlists: Reset RING registers upon resume
>>
>>     commit bafb2f7d4755bf1571bd5e9a03b97f3fc4fe69ae upstream.
>>
>> ended up in v4.9.9 considering that the upstream commit is not annotated
>> for stable, it has no Fixes: tags, and I can't find any backport
>> requests or even notifications for it in my mails. (Admittedly I'm not
>> subscribed on stable@, but I'd expect our lists, maintainers or
>> developers be Cc'd.)
>
> Eric sent this to the stable list a few times, my mistake for not seeing
> he hadn't also cc:ed the developer list.
>
> Want me to revert it?
>
> thanks,
>
> greg k-h

My apologies. I'm new to requesting stable patches, but I thought
sending to the stable mailing lists would keep the proper folks in the
loop. Sorry about that.

The bug that the commit fixes has quite a long documentation trail:

[BAT execlists] Sporadic - gem_exec_suspend basic-s4 GPU hang after resume
https://bugs.freedesktop.org/show_bug.cgi?id=96526

I've had problems with that one and this one that is not fixed in 4.10.x stable:

[Regression BDW] kernel panic in Intel i915 module, complete system
freeze in 4.10-rc2
https://bugs.freedesktop.org/show_bug.cgi?id=99295

Thanks,
Eric