[Intel-gfx] [PATCH 1/3] drm/i915: Use render class for MI_SET_CONTEXT

[Chris Wilson]

Quoting Stuart Summers (2019-08-13 19:00:18)
> On Tue, 2019-08-13 at 18:54 +0100, Chris Wilson wrote:
> > Quoting Stuart Summers (2019-08-13 18:41:19)
> > > Replace GEM_BUG_ON with explicit check for render class
> > > when doing the kernel context switch.
> > > 
> > > Signed-off-by: Stuart Summers <stuart.summers at intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/gt/intel_ringbuffer.c | 4 +---
> > >  1 file changed, 1 insertion(+), 3 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/gt/intel_ringbuffer.c
> > > b/drivers/gpu/drm/i915/gt/intel_ringbuffer.c
> > > index 409d764f8c6d..04ea9bbb88ce 100644
> > > --- a/drivers/gpu/drm/i915/gt/intel_ringbuffer.c
> > > +++ b/drivers/gpu/drm/i915/gt/intel_ringbuffer.c
> > > @@ -1781,9 +1781,7 @@ static int switch_context(struct i915_request
> > > *rq)
> > >                 }
> > >         }
> > >  
> > > -       if (rq->hw_context->state) {
> > > -               GEM_BUG_ON(engine->id != RCS0);
> > > -
> > > +       if (engine->class == RENDER_CLASS && rq->hw_context->state) 
> > > {
> > 
> > It would come as some surprise for this not to be rcs0. I don't think
> > we
> > are prepared for that on legacy HW :)
> 
> Heh, I will admit that this isn't a strict requirement but thought it
> would be nice to have. If you're opposed we can drop this.

I think this is more a summation of what was going through the
programmers mind at the time "this had better be rcs0 or we've screwed
up badly and I have no idea what's going on or how the HW is going to
respond" :)
-Chris