[PATCH] Revert "drm/i915: GFX_MODE Flush TLB Invalidate Mode must be '1' for scanline waits"

[Brad Figg]

On 04/23/2013 05:14 AM, Luis Henriques wrote:
> On Tue, Apr 23, 2013 at 05:59:49AM -0600, Tim Gardner wrote:
>> On 04/23/2013 02:53 AM, Luis Henriques wrote:
>>> On Mon, Apr 22, 2013 at 04:23:17PM -0500, Steve Conklin wrote:
>>>> This reverts commit 30ae292ec68402c773ddc8c80f83f7cd84289a39.
>>>>
>>>> This has been shown to cause GPU hangs
>>>> ---
>>>>  drivers/gpu/drm/i915/intel_ringbuffer.c |    5 -----
>>>>  1 file changed, 5 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c
>>>> index c3654ff..fbaa785 100644
>>>> --- a/drivers/gpu/drm/i915/intel_ringbuffer.c
>>>> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c
>>>> @@ -422,11 +422,6 @@ static int init_render_ring(struct intel_ring_buffer *ring)
>>>>  	if (INTEL_INFO(dev)->gen >= 6)
>>>>  		I915_WRITE(MI_MODE, GFX_MODE_ENABLE(ASYNC_FLIP_PERF_DISABLE));
>>>>
>>>> -	/* Required for the hardware to program scanline values for waiting */
>>>> -	if (INTEL_INFO(dev)->gen == 6)
>>>> -		I915_WRITE(GFX_MODE,
>>>> -			   GFX_MODE_ENABLE(GFX_TLB_INVALIDATE_ALWAYS));
>>>> -
>>>>  	if (IS_GEN7(dev))
>>>>  		I915_WRITE(GFX_MODE_GEN7,
>>>>  			   GFX_MODE_DISABLE(GFX_TLB_INVALIDATE_ALWAYS) |
>>>> --
>>>> 1.7.9.5
>>>>
>>>>
>>>> --
>>>> kernel-team mailing list
>>>> kernel-team at lists.ubuntu.com
>>>> https://lists.ubuntu.com/mailman/listinfo/kernel-team
>>>
>>> Comment 99 in bug #1167114 refers to a debian bug that seems to be a
>>> duplicate.  And the solution was commit
>>> 054430e773c9a1e26f38e30156eff02dedfffc17 (fbcon: fix locking harder).
>>> Maybe its worth trying a kernel with this fix.
>>>
>>> (This commit is already in 3.5.y, so I should have already identified
>>> it as a possible fix for these bugs... My bad, I've queued it without
>>> taking a look at the full context.)
>>>
>>> Cheers,
>>> --
>>> Luis
>>>
>>
>> Is that really related ? It seems like it might be a different bug
>> altogether since most of the reporters don't have issues until well
>> after boot.
> 
> Well, hard to say... the bugs in LP are now really messy and, as Steve
> already said, we're almost for sure dealing here with more than one
> issue.
> 
> So, maybe our best option is to go ahead and revert this commit.  And
> probably also the other (5?) we've added last cycle.  Next SRU cycle
> we'll have the 054430e773c9a1e26f38e30156eff02dedfffc17 from stable
> updates.
> 
> Cheers,
> --
> Luis
> 

I'm only talking about Quantal here.

The relevant revert is for 4c443ec9afe7f6fab41106c617136aca44d69a7b
for which Steve will submit a SRU request.

This upstream commit supposedly fixes an issue but seems to be causing
other issues. We'll just have to see if reverting it helps or hurts
us overall.

I've seen other people suggest reverting the other 5 drm/i915 patches
but I've not seen any testing that shows these are bad and that reverting
them would improve things for anyone.

Do we know if 054430e773c9a1e26f38e30156eff02dedfffc17 does in fact fix
any of this or are we just hoping?

Brad
-- 
Brad Figg brad.figg at canonical.com http://www.canonical.com