[Intel-gfx] [PATCH] drm/i915: Align tiled scanouts from stolen memory to 256k in the GTT

[Chris Wilson]

For unfathomable reasons this alignment appears to be required for tiled
scanouts being read from stolen memory. I can find no reference in the
w/a db to support this requirement, but the evidence of my own eyes says
this prevents many headaches.

Note that I have not tricked anything older than Sandybridge into using
stolen tiled scanouts, so the extra alignment may be required there as
well.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
---
 drivers/gpu/drm/i915/intel_display.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 6b7ce06..a7573f2 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1848,6 +1848,8 @@ intel_pin_and_fence_fb_obj(struct drm_device *dev,
 	case I915_TILING_X:
 		/* pin() will align the object as required by fence */
 		alignment = 0;
+		if (obj->stolen && INTEL_INFO(dev)->gen >= 6)
+			alignment = 256 * 1024;
 		break;
 	case I915_TILING_Y:
 		/* Despite that we check this in framebuffer_init userspace can
-- 
1.8.4.rc2