linux-kernel - [PATCH] drm/i915/skl: Fix redundant cursor update, fix cursor underruns

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Message-Id: <1468620836-11735-1-git-send-email-cpaul@redhat.com>
Date:	Fri, 15 Jul 2016 18:13:56 -0400
From:	Lyude <cpaul@...hat.com>
To:	intel-gfx@...ts.freedesktop.org
Cc:	Lyude <cpaul@...hat.com>,
	Radhakrishna Sripada <radhakrishna.sripada@...el.com>,
	Hans de Goede <hdegoede@...hat.com>, stable@...r.kernel.org,
	Daniel Vetter <daniel.vetter@...el.com>,
	Jani Nikula <jani.nikula@...ux.intel.com>,
	David Airlie <airlied@...ux.ie>,
	dri-devel@...ts.freedesktop.org (open list:INTEL DRM DRIVERS (excluding
	Poulsbo, Moorestow...), linux-kernel@...r.kernel.org (open list))
Subject: [PATCH] drm/i915/skl: Fix redundant cursor update, fix cursor underruns

At long last, the time has finally come for Skylake users to plug their
external displays back in.

During intel_atomic_commit() on Skylake, we've actually been arming the
registers to update the cursor information twice instead of just once.
Once in i9xx_update_cursor(), and once in skl_wm_flush_pipe(). This
isn't actually necessary, and removing the later update in
skl_wm_flush_pipe() has completely stopped the underruns on this T460p
from occurring when moving the mouse cursor from one monitor to another.

Signed-off-by: Lyude <cpaul@...hat.com>
Cc: Radhakrishna Sripada <radhakrishna.sripada@...el.com>
Cc: Hans de Goede <hdegoede@...hat.com>
Cc: stable@...r.kernel.org
---
 drivers/gpu/drm/i915/intel_pm.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 7ac71ec..4771a03 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3860,7 +3860,6 @@ skl_wm_flush_pipe(struct drm_i915_private *dev_priv, enum pipe pipe, int pass)
 		I915_WRITE(PLANE_SURF(pipe, plane),
 			   I915_READ(PLANE_SURF(pipe, plane)));
 	}
-	I915_WRITE(CURBASE(pipe), I915_READ(CURBASE(pipe)));
 }
 
 static bool
-- 
2.7.4