Re: [PATCH] drm/i915/bdw: Render moot context reset and switch with Execlists

Chris Wilson
2014-08-26T05:59:56Z

On Mon, Aug 25, 2014 at 10:39:39PM +0200, Daniel Vetter wrote:
> On Wed, Aug 20, 2014 at 04:36:05PM +0100, Chris Wilson wrote:
> > On Wed, Aug 20, 2014 at 04:29:24PM +0100, Thomas Daniel wrote:
> > > These two functions make no sense in an Logical Ring Context & Execlists
> > > world.
> > >
> > > v2: We got rid of lrc_enabled and centralized everything in the sanitized
> > > i915.enable_execlists instead.
> > >
> > > Signed-off-by: Oscar Mateo <oscar.mateo@intel.com>
> > >
> > > v3: Rebased. Corrected a typo in comment for i915_switch_context and
> > > added a comment that it should not be called in execlist mode. Added
> > > WARN_ON if i915_switch_context is called in execlist mode. Moved check
> > > for execlist mode out of i915_switch_context and into callers. Added
> > > comment in context_reset explaining why nothing is done in execlist
> > > mode.
> >
> > No, this is not the way. The requirement is to reduce the number of
> > special cases not increase them. These should be evaluated to be no-ops
> > when execlists is used.
>
> I think it's ok-ish for now. Maybe we need to reconsider when we wire up
> lrc reclaim - which is the real user of the switch_context in gpu_idle.
> The problem I have though is that I can't parse the subject of the patch,
> someone please translate that to simplified English for me. I can do the
> replacement while applying.

No, it is not. execlists is badly designed and this is a further symptom
of that.
-Chris

--
Chris Wilson, Intel Open Source Technology Centre