drm/i915: implement WaDisableVLVClockGating_VBIIssue on VLV

This allows us to get the right vblank interrupt frequency.

v2: pull in register definition

Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Reviewed-by: Antti Koskipää <antti.koskipaa@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

1 files changed, 7 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 871bfe49b91..10e6d6c2196 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3755,6 +3755,13 @@ static void valleyview_init_clock_gating(struct drm_device *dev)
                    PIPEA_HLINE_INT_EN | PIPEA_VBLANK_INT_EN |
                    SPRITEB_FLIPDONE_INT_EN | SPRITEA_FLIPDONE_INT_EN |
                    PLANEA_FLIPDONE_INT_EN);
+
+        /*
+         * WaDisableVLVClockGating_VBIIssue
+         * Disable clock gating on th GCFG unit to prevent a delay
+         * in the reporting of vblank events.
+         */
+        I915_WRITE(VLV_GUNIT_CLOCK_GATE, GCFG_DIS);
 }
 
 static void g4x_init_clock_gating(struct drm_device *dev)