[Intel-gfx] [PATCH 3/6] drm/i915: Don't emit semaphore wait if wrap happened

[Paulo Zanoni]

Hi

2012/12/6 Daniel Vetter <daniel at ffwll.ch>:
> On Wed, Dec 5, 2012 at 9:44 PM, Paulo Zanoni <przanoni at gmail.com> wrote:
>> 2012/12/4 Mika Kuoppala <mika.kuoppala at linux.intel.com>:
>>> If wrap just happened we need to prevent emitting waits for
>>> pre wrap values. Detect this and emit no-ops instead.
>>>
>>> v2: Use olr > seqno to detect wrap instead of *seqno == 0
>>> as suggested by Chris Wilson.
>>
>> This commit introduces a bug on Haswell. Now when I'm typing my
>> password on GDM the screen keeps doing wrong rendering. It "blinks
>> blue". After logging in I don't see more prodrm/i915: Set initial seqno value close to wrap boundaryblems.
>
> Just now I've taken out "drm/i915: Set initial seqno value close to
> wrap boundary" since QA complained that it regresses things. Does that
> help for you, too?

It helps: besides the "wrong rendering at GDM screen" I was also
getting  GPU hangs (when starting X, when running dmesg, when alt+tab,
etc), and it seems with today's dinq I don't get the gpu hangs
anymore. I still get the "wrong rendering" problem and it goes away if
we revert the "Don't emit semaphore wait  if wrap happened".

> -Daniel
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch



-- 
Paulo Zanoni