3.15-rc2: i915 regression: only top 20% of screen works in X

[Pavel Machek]

On Thu 2014-04-24 08:03:04, Daniel Vetter wrote:
> On Thu, Apr 24, 2014 at 7:50 AM, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> > That says that i915.ko failed to initialise the GPU (or rather the GPU
> > wasn't responding) and bailed during module load. The key line here is
> >
> > [drm:init_ring_common] *ERROR* render ring initialization failed ctl
> > 0001f001 head 00002034 tail 00000000 start 0012f000
> >
> > Jiri has been seeing a similar issue creep in during resume, but it is
> > not reliable enough to bisect. Is your boot failure reliable enough to
> > bisect? Also drm-intel-nightly should mitigate this failure and allow
> > i915.ko to continue to load and run X, which would be worth testing to
> > make sure that works as intended.
> 
> Oh right, g4x going beserk :( Apparently something changed in 3.15
> somewhere which made this much more likely, but like Chris said in
> Jiri's case it's too unreliable to reproduce for a bisect. We've had
> this come&go pretty much ever since kms support was merged and never
> tracked it down.

So far I went back to 3.14, and yes, graphics works there.

Back to 3.15, put it to smaller monitor. This time, top 30% of screen
works, and last working scanline is copied to the rest 60% of
screen. [With the exception of mouse cursor, that somehow affects that
magically.]

> The bug is https://bugs.freedesktop.org/show_bug.cgi?id=76554
> 
> Like Chris said please test latest drm-intel-nighlty from
> http://cgit.freedesktop.org/drm-intel to make sure that the recently
> merged mitigation measures work properly. But those won't get your gpu
> back, only the display and it's only for 3.16. We're still hunting a
> proper fix for 3.15.

So you know where the bug is or not?

> And if you can indeed reliably reproduce this a bisect could be really useful.

I'm confused. And yes, it seems reliable. But I'm not sure if I see
same bug you are talking about.
									Pavel
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