drm/i915/gen9: Add WaEnableChickenDCPR

Workaround for display underrun issues with Y & Yf Tiling.
Set this on all gen9 as stated by bspec.

v2: proper workaround name

References: HSD#2136383, BSID#857
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>
Reviewed-by: Matthew Auld <matthew.auld@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1465309159-30531-22-git-send-email-mika.kuoppala@intel.com
(cherry picked from commit 590e8ff04bc0182dce97228e5e352d6413d80456)
Signed-off-by: Mika Kuoppala <mika.kuoppala@intel.com>

2 files changed, 7 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 349470d0ff1c..87655ac6a39c 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -6059,6 +6059,9 @@ enum skl_disp_power_wells {
 #define HSW_NDE_RSTWRN_OPT      _MMIO(0x46408)
 #define  RESET_PCH_HANDSHAKE_ENABLE     (1<<4)
 
+#define GEN8_CHICKEN_DCPR_1             _MMIO(0x46430)
+#define   MASK_WAKEMEM                  (1<<13)
+
 #define SKL_DFSM                        _MMIO(0x51000)
 #define SKL_DFSM_CDCLK_LIMIT_MASK       (3 << 23)
 #define SKL_DFSM_CDCLK_LIMIT_675        (0 << 23)
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 3f0f1880d4af..362800ba63a8 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -64,6 +64,10 @@ static void gen9_init_clock_gating(struct drm_device *dev)
 
         I915_WRITE(GEN8_CONFIG0,
                    I915_READ(GEN8_CONFIG0) | GEN9_DEFAULT_FIXES);
+
+        /* WaEnableChickenDCPR:skl,bxt,kbl */
+        I915_WRITE(GEN8_CHICKEN_DCPR_1,
+                   I915_READ(GEN8_CHICKEN_DCPR_1) | MASK_WAKEMEM);
 }
 
 static void bxt_init_clock_gating(struct drm_device *dev)