[Intel-gfx] [PATCH] drm/i915: Click the ACTHD three times to go home

[Mika Kuoppala]

Chris Wilson <chris at chris-wilson.co.uk> writes:

> On Mon, Mar 27, 2017 at 04:19:58PM +0300, Mika Kuoppala wrote:
>> Chris Wilson <chris at chris-wilson.co.uk> writes:
>> 
>> > On Mon, Mar 27, 2017 at 01:12:30PM +0300, Mika Kuoppala wrote:
>> >> Chris Wilson <chris at chris-wilson.co.uk> writes:
>> >> 
>> >> > One POSTING_READ of ACTHD may not be enough to ensure that the seqno
>> >> > write has been posted from the GPU and is now visible. So do three!
>> >> >
>> >> 
>> >> Is this about posting read triggering or just adding enough delay
>> >> that the write gets through?
>> >
>> > It's purely about a delay that we guess will cover 99.9999% of cases.
>> 
>> Acked-by: Mika Kuoppala <mika.kuoppala at intel.com>
>
> Thanks, for checking over the idea. I'm going to apply it to
> topic/core-for-CI for some extended soak testing and see if that
> silences fi-snb-2600

Another thing that would be worth testing is to force a latency guarantee
through pm_qos.

-Mika