[PATCH 14/15] drm/i915: skl nv12 wa - NV12 to RGB switch

Chandra Konduru
2015-09-09T23:02:45Z

Switching format from NV12 to RGB can result in display underrun
and corruption. This workaround sets bits 15 & 19 to 1 in
CLKGATE_DIS_PSL register to address transition underrun.

v2:
-Move workaround to init clock gating (Ville)

Signed-off-by: Chandra Konduru <chandra.konduru@intel.com>
---
drivers/gpu/drm/i915/i915_reg.h | 8 ++++++++
drivers/gpu/drm/i915/intel_pm.c | 8 ++++++++
2 files changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index d20f235..2e2636d 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -5366,6 +5366,14 @@ enum skl_disp_power_wells {
#define CHICKEN_DCPR_1 0x46430
#define IDLE_WAKEMEM_MASK (1 << 13)

+#define CLKGATE_DIS_PSL_A 0x46520
+#define CLKGATE_DIS_PSL_B 0x46524
+#define CLKGATE_DIS_PSL_C 0x46528
+#define DUPS1_GATING_DIS (1 << 15)
+#define DUPS2_GATING_DIS (1 << 19)
+#define DUPS3_GATING_DIS (1 << 23)
+#define CLKGATE_DIS_PSL(pipe) _PIPE(pipe, CLKGATE_DIS_PSL_A, CLKGATE_DIS_PSL_B)
+
/* SKL new cursor registers */
#define _CUR_BUF_CFG_A 0x7017c
#define _CUR_BUF_CFG_B 0x7117c
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 8a36ab9..9a3deed 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -63,6 +63,14 @@ static void gen9_init_clock_gating(struct drm_device *dev)
/* WaDisableKillLogic:bxt,skl */
I915_WRITE(GAM_ECOCHK, I915_READ(GAM_ECOCHK) |
ECOCHK_DIS_TLB);
+
+ /*
+ * Switching format from NV12 to RGB can result in display underrun
+ * and corruption. This workaround sets bits 15 & 19 to 1 in
+ * CLKGATE_DIS_PSL register to address transition underrun.
+ */
+ I915_WRITE(CLKGATE_DIS_PSL(PIPE_A), DUPS1_GATING_DIS | DUPS2_GATING_DIS);
+ I915_WRITE(CLKGATE_DIS_PSL(PIPE_B), DUPS1_GATING_DIS | DUPS2_GATING_DIS);
}

static void skl_init_clock_gating(struct drm_device *dev)
--
1.7.9.5