[Intel-gfx] [PATCH 1/2] drm/i915: clear GFX_MODE on IVB at init time

[Kenneth Graunke]

On 08/12/2011 03:28 PM, Jesse Barnes wrote:
> On Fri, 12 Aug 2011 15:18:09 -0700
> Jesse Barnes <jbarnes at virtuousgeek.org> wrote:
> 
>> On Fri, 12 Aug 2011 14:55:32 -0700
>> Jesse Barnes <jbarnes at virtuousgeek.org> wrote:
>>
>>> GFX_MODE controls important behavior like PPGTT, run lists, and TLB
>>> invalidate behavior.  On the SDV I'm using, the TLB invalidation mode
>>> was defaulting to "pipe control only" which meant regular MI_FLUSHes
>>> wouldn't actually flush the TLB, leading to all sorts of stale data
>>> getting used.
>>>
>>> So initialize it to 0 at ring buffer init time until we actually use
>>> PIPE_CONTROL for TLB invalidation.
>>
>> Ignore this one, see below for an updated patch that uses bit
>> definitions and makes sure the register gets reset at GPU reset time as
>> well.
> 
> Ignore the last one too.  Third time's the charm!

Tested-by: Kenneth Graunke <kenneth at whitecape.org>

With drm-intel-next, I've been seeing frequent but intermittent
rendering corruption in GNOME Terminal, rendercheck failures, and the
occasional kernel crash.

After applying the patch, I was able to run for an entire day without
any crashes or rendering corruption.  To double check, I reverted this
patch and was immediately able to reproduce my earlier problems.

With this patch and C0 hardware, my system seems quite stable.  Thanks
Jesse!