Pageflipping bugs in drm-next on at least Ironlake and Ivybridge.

Pageflipping bugs in drm-next on at least Ironlake and Ivybridge.

[Mario Kleiner]

Since i pulled the current drm-next tree i see strong flicker and visual 
corruption during pageflipping, both in my own app, but also in KDE4 and 
KDE5 Plasma with desktop composition enabled. This happens on both Intel 
HD Ironake mobile (Apple MBP 2010) and HD-4000 Ivybridge mobile (Apple 
macMini 2012).

It looks like page flips are not waiting properly for rendering to 
complete, showing partially rendered frames at flip time.

If i revert Daniel's commit that switches legacy pageflips from the old 
code path to the atomic code, all problems disappear, so apparently the 
atomic code for Intel is not quite ready at least on those parts?

In case this helps: As i was also testing DRI3/Present + PRIME on the 
hybrid graphics MBP, if i use the Intel HD as display gpu and the 
NVidia/nouveau as render offload gpu i don't get any corruption/flicker 
even with the atomic pageflip code for legacy pageflips. Iow. the path 
using dmabuf fence wait in intel_prepare_plane_fb works fine.

thanks,
-mario
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Re: Pageflipping bugs in drm-next on at least Ironlake and Ivybridge.

[Chris Wilson]

On Wed, Jul 06, 2016 at 12:17:55PM +0200, Mario Kleiner wrote:
> Since i pulled the current drm-next tree i see strong flicker and
> visual corruption during pageflipping, both in my own app, but also
> in KDE4 and KDE5 Plasma with desktop composition enabled. This
> happens on both Intel HD Ironake mobile (Apple MBP 2010) and HD-4000
> Ivybridge mobile (Apple macMini 2012).
> 
> It looks like page flips are not waiting properly for rendering to
> complete, showing partially rendered frames at flip time.
> 
> If i revert Daniel's commit that switches legacy pageflips from the
> old code path to the atomic code, all problems disappear, so
> apparently the atomic code for Intel is not quite ready at least on
> those parts?

Exactly right, we've reverted the enabling patch for the time being.
Daniel Stone has spotted the likely problem, but we also want to review
the handling of state/old_state to see if the same problem has cropped
up elsewhere.
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre
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Re: Pageflipping bugs in drm-next on at least Ironlake and Ivybridge.

[Mario Kleiner]

On 07/06/2016 03:05 PM, Chris Wilson wrote:
> On Wed, Jul 06, 2016 at 12:17:55PM +0200, Mario Kleiner wrote:
>> Since i pulled the current drm-next tree i see strong flicker and
>> visual corruption during pageflipping, both in my own app, but also
>> in KDE4 and KDE5 Plasma with desktop composition enabled. This
>> happens on both Intel HD Ironake mobile (Apple MBP 2010) and HD-4000
>> Ivybridge mobile (Apple macMini 2012).
>>
>> It looks like page flips are not waiting properly for rendering to
>> complete, showing partially rendered frames at flip time.
>>
>> If i revert Daniel's commit that switches legacy pageflips from the
>> old code path to the atomic code, all problems disappear, so
>> apparently the atomic code for Intel is not quite ready at least on
>> those parts?
>
> Exactly right, we've reverted the enabling patch for the time being.
> Daniel Stone has spotted the likely problem, but we also want to review
> the handling of state/old_state to see if the same problem has cropped
> up elsewhere.
> -Chris
>

Ah ok, now i see it in drm-intel-next-queued. I'm probably not adding 
anything new here, but wrt. your crc based tests not catching it, while 
it happens all the time for me under KDE, in my own fullscreen app, it 
only obviously happens for some tests, the more graphics heavy ones not 
others, so probably (gfx-)load dependent? Maybe the tests don't put 
enough work onto the gpu to still keep it rendering at flip time.

-mario
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