Re: [PATCH] drm/i915/skl: Use correct use counters for force wakes

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 09/30/2014 03:57 PM, Chris Wilson wrote:
> On Tue, Sep 30, 2014 at 03:08:02PM +0100, Tvrtko Ursulin wrote:
>> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>>
>> Write and reads following the block changed use engine specific use counters
>> and unless that is matched here force wake use counting goes bad. Same
>> force wake is attempted to be taken twice which leads to at least time outs.
>>
>> NOTE: Depending on feedback from hardware designers it may not be necessary
>> to grab force wakes on Gen9 here. But for Gen8 it is needed due to a race
>> between RC6 and ELSP writes.
>>
>> v2: Added blitter force wake engine and made more future proof.
>>      Added commit note.
>
> Speaking of futureproofing, what did you think of my patch to remove the
> duplicated counting logic?

[For reference it is called "[PATCH] drm/i915: Reduce duplicated 
forcewake logic".]

Disclaimer: I don't know this code that well - only had to dig into it a 
few days back when I hit this bug which resulted in my patch.

But from a glance your patch does make it look cleaner and indeed more 
future proof (much better separation between platform specific and 
generic). Does it need a proper review to move it forward?

Regards,

Tvrtko