[Intel-gfx] [PATCH 3/3] drm/i915: Fix i915_ggtt_view_equal to handle rotation correctly

[Chris Wilson]

On Wed, Oct 14, 2015 at 04:08:25PM +0100, Tvrtko Ursulin wrote:
> 
> Hi,
> 
> On 14/10/15 15:51, Daniel Vetter wrote:
> >The rotated view depends upon the rotation paramters, but thus far we
> >didn't bother checking for those. This seems to have been an issue
> >ever since this was introduce in
> >
> >commit fe14d5f4e5468c5b80a24f1a64abcbe116143670
> >Author: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> >Date:   Wed Dec 10 17:27:58 2014 +0000
> >
> >     drm/i915: Infrastructure for supporting different GGTT views per object
> >
> >But userspace is allowed to reuse framebuffer backing storage with
> >different framebuffers with different pixel formats/stride/whatever.
> >And e.g. SNA indeed does this. Hence we must check for all the
> >paramters to match, not just that it's rotated.
> >
> >v2: intel_plane_obj_offset also needs to construct the full view, to
> >avoid fallout since they don't fully match.
> >
> >Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
> >Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
> >---
> >  drivers/gpu/drm/i915/i915_gem_gtt.h  |  2 +-
> >  drivers/gpu/drm/i915/intel_display.c | 10 +++++-----
> >  2 files changed, 6 insertions(+), 6 deletions(-)
> >
> >diff --git a/drivers/gpu/drm/i915/i915_gem_gtt.h b/drivers/gpu/drm/i915/i915_gem_gtt.h
> >index 2e1f6493c9e7..8a36f4fcc676 100644
> >--- a/drivers/gpu/drm/i915/i915_gem_gtt.h
> >+++ b/drivers/gpu/drm/i915/i915_gem_gtt.h
> >@@ -551,7 +551,7 @@ i915_ggtt_view_equal(const struct i915_ggtt_view *a,
> >
> >  	if (a->type != b->type)
> >  		return false;
> >-	if (a->type == I915_GGTT_VIEW_PARTIAL)
> >+	if (a->type != I915_GGTT_VIEW_NORMAL)
> >  		return !memcmp(&a->params, &b->params, sizeof(a->params));
> >  	return true;
> >  }
> >diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> >index 57459fedf216..2a5987ce576c 100644
> >--- a/drivers/gpu/drm/i915/intel_display.c
> >+++ b/drivers/gpu/drm/i915/intel_display.c
> >@@ -2894,16 +2894,16 @@ unsigned long intel_plane_obj_offset(struct intel_plane *intel_plane,
> >  				     struct drm_i915_gem_object *obj,
> >  				     unsigned int plane)
> >  {
> >-	const struct i915_ggtt_view *view = &i915_ggtt_view_normal;
> >+	struct i915_ggtt_view view;
> >  	struct i915_vma *vma;
> >  	unsigned char *offset;
> >
> >-	if (intel_rotation_90_or_270(intel_plane->base.state->rotation))
> >-		view = &i915_ggtt_view_rotated;
> >+	intel_fill_fb_ggtt_view(&view, intel_plane->base.fb,
> >+				intel_plane->base.state);
> >
> >-	vma = i915_gem_obj_to_ggtt_view(obj, view);
> >+	vma = i915_gem_obj_to_ggtt_view(obj, &view);
> >  	if (WARN(!vma, "ggtt vma for display object not found! (view=%u)\n",
> >-		view->type))
> >+		view.type))
> >  		return -1;
> >
> >  	offset = (unsigned char *)vma->node.start;
> >
> 
> As we discussed on IRC I had wrong assumptions when developing this.
> Luckily SNA is not using hardware 90/270 yet so we are safe there.

*by default (since it requires Y-tiling of the frontbuffer and that
makes other accesses very slow and needing workarounds to prevent
overall degredation, for some workloads in particular).
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre