Re: [Intel-gfx] [PATCH v4 4/5] drm/i915/display: consider DG2_RC_CCS_CC when migrating buffers

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Tue, Oct 04, 2022 at 12:51:11PM +0100, Matthew Auld wrote:
> On 04/10/2022 12:28, Ville Syrjälä wrote:
> > On Tue, Oct 04, 2022 at 11:33:10AM +0100, Matthew Auld wrote:
> >> For these types of display buffers, we need to able to CPU access some
> >> part of the backing memory in prepare_plane_clear_colors(). As a result
> >> we need to ensure we always place in the mappable part of lmem, which
> >> becomes necessary on small-bar systems.
> >>
> >> v2(Nirmoy & Ville):
> >>   - Add some commentary for why we need to CPU access the buffer.
> >>   - Split out the other changes, so we just consider the display change
> >>     here.
> >> v3:
> >>   - Handle this in the dpt path.
> >>
> >> Fixes: eb1c535f0d69 ("drm/i915: turn on small BAR support")
> >> Reported-by: Jianshui Yu <jianshui.yu@intel.com>
> >> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> >> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> >> Cc: Nirmoy Das <nirmoy.das@intel.com>
> >> ---
> >>   drivers/gpu/drm/i915/display/intel_fb_pin.c | 24 +++++++++++++++++++--
> >>   1 file changed, 22 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/drivers/gpu/drm/i915/display/intel_fb_pin.c b/drivers/gpu/drm/i915/display/intel_fb_pin.c
> >> index 32206bd359da..8197343300ee 100644
> >> --- a/drivers/gpu/drm/i915/display/intel_fb_pin.c
> >> +++ b/drivers/gpu/drm/i915/display/intel_fb_pin.c
> >> @@ -50,7 +50,18 @@ intel_pin_fb_obj_dpt(struct drm_framebuffer *fb,
> >>   			continue;
> >>   
> >>   		if (HAS_LMEM(dev_priv)) {
> >> -			ret = i915_gem_object_migrate(obj, &ww, INTEL_REGION_LMEM_0);
> >> +			unsigned int flags = obj->flags;
> >> +
> >> +			/*
> >> +			 * For this type of buffer we need to able to read from the CPU
> >> +			 * the clear color value found in the buffer, hence we need to
> >> +			 * ensure it is always in the mappable part of lmem, if this is
> >> +			 * a small-bar device.
> >> +			 */
> >> +			if (intel_fb_rc_ccs_cc_plane(fb) >= 0)
> >> +				flags &= ~I915_BO_ALLOC_GPU_ONLY;
> >> +			ret = __i915_gem_object_migrate(obj, &ww, INTEL_REGION_LMEM_0,
> >> +							flags);
> >>   			if (ret)
> >>   				continue;
> >>   		}
> >> @@ -156,8 +167,17 @@ intel_pin_and_fence_fb_obj(struct drm_framebuffer *fb,
> >>   	ret = i915_gem_object_lock(obj, &ww);
> >>   	if (!ret && phys_cursor)
> >>   		ret = i915_gem_object_attach_phys(obj, alignment);
> >> -	else if (!ret && HAS_LMEM(dev_priv))
> >> +	else if (!ret && HAS_LMEM(dev_priv)) {
> >> +		/*
> >> +		 * For this type of ccs buffer we need to able to read from the
> >> +		 * CPU the clear color value found in the buffer, which might
> >> +		 * require moving to the mappable part of lmem first, but here
> >> +		 * we should be using dpt for this.
> >> +		 */
> >> +		WARN_ON_ONCE(intel_fb_rc_ccs_cc_plane(fb) >= 0);
> > 
> > DPT isn't availalable on DG1.
> 
> Hmm, does it also support the DG2_RC_CCS_CC modifier?

I believe it should support I915_FORMAT_MOD_Y_TILED_GEN12_RC_CCS_CC.

> 
> > 
> >> +
> >>   		ret = i915_gem_object_migrate(obj, &ww, INTEL_REGION_LMEM_0);
> >> +	}
> >>   	if (!ret)
> >>   		ret = i915_gem_object_pin_pages(obj);
> >>   	if (ret)
> >> -- 
> >> 2.37.3
> > 

-- 
Ville Syrjälä
Intel