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

[Jani Nikula]

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.)

BR,
Jani.


>
> Regards,
> Eric
>
> On Mon, Mar 13, 2017 at 6:23 PM, Damian Dominik Martinez Dreyer
> <damian at mailbox.org> wrote:
>> I am writing regarding this kernel patch: https://git.kernel.org/pub/sc
>> m/linux/kernel/git/stable/stable-queue.git/tree/releases/4.9.9/drm-
>> i915-execlists-reset-ring-registers-upon-resume.patch .
>>
>> I have identified this by bisect to be the cause of a suspend and
>> resume issue. Please see https://github.com/kxv/linux49.9 for the
>> bisect history.
>>
>> After this change, a Laptop (HP Spectre x360) with Intel HD Graphics
>> 520 will wake up from suspend to a blank screen.
>>
>> Please also see this thread on the manjaro linux forum: https://forum.m
>> anjaro.org/t/linux-4-9-9-breaks-hibernation-4-9-8-works/17499 .
>>
>>
>> Best regards
>> Damian Dominik Martinez Dreyer
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> Intel-gfx at lists.freedesktop.org
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-- 
Jani Nikula, Intel Open Source Technology Center