[Intel-gfx] [PATCH 09/23] drm/i915/edp: Add WaKVMNotificationOnConfigChange:bdw, skl

[Mika Kuoppala]

According to bspec this workaround helps to reduce lag and improve
performance on edp.

References: HSD#2134579
Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com>
---
 drivers/gpu/drm/i915/i915_reg.h | 3 +++
 drivers/gpu/drm/i915/intel_pm.c | 8 ++++++++
 2 files changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index e3077259541a..1f84c2ff3563 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -6035,6 +6035,9 @@ enum skl_disp_power_wells {
 #define  FORCE_ARB_IDLE_PLANES	(1 << 14)
 #define  SKL_EDP_PSR_FIX_RDWRAP	(1 << 3)
 
+#define CHICKEN_PAR2_1		_MMIO(0x42090)
+#define  KVM_CONFIG_CHANGE_NOTIFICATION_SELECT	(1 << 14)
+
 #define _CHICKEN_PIPESL_1_A	0x420b0
 #define _CHICKEN_PIPESL_1_B	0x420b4
 #define  HSW_FBCQ_DIS			(1 << 22)
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index fc34add6ab82..5d9b7ff9dc18 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -6870,6 +6870,10 @@ static void skylake_init_clock_gating(struct drm_device *dev)
 	/* See Bspec note for PSR2_CTL bit 31, Wa#828:skl */
 	I915_WRITE(CHICKEN_PAR1_1,
 		   I915_READ(CHICKEN_PAR1_1) | SKL_EDP_PSR_FIX_RDWRAP);
+
+	/* WaKVMNotificationOnConfigChange:skl */
+	I915_WRITE(CHICKEN_PAR2_1, I915_READ(CHICKEN_PAR2_1)
+		   | KVM_CONFIG_CHANGE_NOTIFICATION_SELECT);
 }
 
 static void broadwell_init_clock_gating(struct drm_device *dev)
@@ -6916,6 +6920,10 @@ static void broadwell_init_clock_gating(struct drm_device *dev)
 	 */
 	I915_WRITE(HSW_GTT_CACHE_EN, GTT_CACHE_EN_ALL);
 
+	/* WaKVMNotificationOnConfigChange:bdw */
+	I915_WRITE(CHICKEN_PAR2_1, I915_READ(CHICKEN_PAR2_1)
+		   | KVM_CONFIG_CHANGE_NOTIFICATION_SELECT);
+
 	lpt_init_clock_gating(dev);
 }
 
-- 
2.5.0