[Intel-gfx] [PATCH 1/2] drm/i915: Don't require primary->fb in intel_crtc_active()

[Matt Roper]

Universal planes allow us to have an active CRTC without a primary plane
framebuffer bound.  Drop the test for primary->fb from
intel_crtc_active() since we can clearly have active CRTC's without a
framebuffer, and this check is now interfering with watermark
calculations when we try to re-enable the primary plane.

Note that commit

        commit 0fda65680e92545caea5be7805a7f0a617fb6c20
        Author: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
        Date:   Fri Feb 27 15:12:35 2015 +0000

            drm/i915/skl: Update watermarks for Y tiling

adds a test for primary plane enable/disable to trigger a watermark
update (previously we ignored updates to primary planes, which wasn't
really correct, but we got lucky since we always pretended the primary
plane was on).  Tvrtko's patch tries to update watermarks when we
re-enable the primary plane, but that watermark computation gets aborted
early because intel_crtc_active() always returns false when the primary
plane is disabled; this leads to watermark underruns (at least on
platforms with ILK-style watermark code).

Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Signed-off-by: Matt Roper <matthew.d.roper at intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 589addf..92cb2ff 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -893,11 +893,8 @@ bool intel_crtc_active(struct drm_crtc *crtc)
 	 *
 	 * We can ditch the adjusted_mode.crtc_clock check as soon
 	 * as Haswell has gained clock readout/fastboot support.
-	 *
-	 * We can ditch the crtc->primary->fb check as soon as we can
-	 * properly reconstruct framebuffers.
 	 */
-	return intel_crtc->active && crtc->primary->fb &&
+	return intel_crtc->active &&
 		intel_crtc->config->base.adjusted_mode.crtc_clock;
 }
 
-- 
1.8.5.1