drm/i915: Add a FIXME about FBC vs. fence. 90/270 degree rotation

vsyrjala · vsyrjala · commit 61b8b359d02e · 2018-02-22T18:11:14.000+02:00
Currently the FBC code doesn't handle the 90/270 degree rotated case correctly. We would need the GTT tracking to monitor the fence on the normal GTT view (the rotated view doesn't even have a fence). Not quite sure how we should program the fence Y offset etc. in that case. For now we'll end up disabling FBC with 90/270 degree rotation. Add a FIXME to remind people about this fact. v2: Reword the text (Chris) Move the FIXME to the fbc code Cc: Chris Wilson <chris@chris-wilson.co.uk> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com> Link: https://patchwork.freedesktop.org/patch/msgid/20180221160235.11134-7-ville.syrjala@linux.intel.com Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
diff --git a/drivers/gpu/drm/i915/intel_fbc.c b/drivers/gpu/drm/i915/intel_fbc.c
@@ -810,6 +810,12 @@ static bool intel_fbc_can_activate(struct intel_crtc *crtc)
 	 * Note that is possible for a tiled surface to be unmappable (and
 	 * so have no fence associated with it) due to aperture constaints
 	 * at the time of pinning.
+	 *
+	 * FIXME with 90/270 degree rotation we should use the fence on
+	 * the normal GTT view (the rotated view doesn't even have a
+	 * fence). Would need changes to the FBC fence Y offset as well.
+	 * For now this will effecively disable FBC with 90/270 degree
+	 * rotation.
 	 */
 	if (!(cache->flags & PLANE_HAS_FENCE)) {
 		fbc->no_fbc_reason = "framebuffer not tiled or fenced";
