[Intel-gfx] [PATCH 2/3] drm/i915: Always flush the dirty CPU cache when pinning the scanout

[Chris Wilson]

On Tue, Nov 08, 2016 at 01:33:41PM +0200, Ville Syrjälä wrote:
> On Sun, Nov 06, 2016 at 01:00:00PM +0000, Chris Wilson wrote:
> > -	i915_gem_object_flush_cpu_write_domain(obj);
> > +	if (obj->cache_dirty || obj->base.write_domain == I915_GEM_DOMAIN_CPU)
> > +		i915_gem_clflush_object(obj, true);
> > +	intel_fb_obj_flush(obj, false, ORIGIN_CPU);
> 
> So one slight change in behaviour is that we won't clear the write domain
> here, but that's fine since we'll clear it below anyway.
> 
> The other is that we now call intel_fb_obj_flush() unconditionally,
> whereas before we only called if when the bo was in the CPU write
> domain. Hmm. Should we keep it conditional?

I was thinking that we should call it in the case we deferred clflush,
and I was wanting to make the preflip path closer to dirtyfb. Since to
me they both demark the frame boundary and the preparatory flushing
should be more or less the same.

> >  	old_write_domain = obj->base.write_domain;
> >  	old_read_domains = obj->base.read_domains;
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index 92ab01f33208..47233b242c99 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -15698,6 +15698,8 @@ static int intel_user_framebuffer_dirty(struct drm_framebuffer *fb,
> >  	struct drm_i915_gem_object *obj = intel_fb->obj;
> >  
> >  	mutex_lock(&dev->struct_mutex);
> > +	if (obj->pin_display && obj->cache_dirty)
> > +		i915_gem_clflush_object(obj, true);
> >  	intel_fb_obj_flush(obj, false, ORIGIN_DIRTYFB);
> >  	mutex_unlock(&dev->struct_mutex);

-- 
Chris Wilson, Intel Open Source Technology Centre