[PATCH 17/17] drm/i915: Display WA 827

[Vidya Srinivas]

Display WA 827 applies to GEN9 (excluede GLK) and CNL.
Switching the plane format from NV12 to RGB and leaving system idle
results in display underrun and corruption.
WA: Set the bit 15 & bit 19 to 1b in the CLKGATE_DIS_PSL
register for the pipe in which NV12 plane is enabled.

Signed-off-by: Chandra Konduru <chandra.konduru at intel.com>
Signed-off-by: Nabendu Maiti <nabendu.bikash.maiti at intel.com>
Signed-off-by: Vidya Srinivas <vidya.srinivas at intel.com>
---
 drivers/gpu/drm/i915/i915_reg.h      |  3 +++
 drivers/gpu/drm/i915/intel_display.c | 31 +++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 8e61b68..dd8ee98 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -3939,6 +3939,9 @@ enum {
 #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   DPF_GATING_DIS		(1 << 10)
 #define   DPF_RAM_GATING_DIS		(1 << 9)
 #define   DPFR_GATING_DIS		(1 << 8)
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 941f00d..f5fdf8a 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -504,6 +504,21 @@ static const struct intel_limit intel_limits_bxt = {
 	.p2 = { .p2_slow = 1, .p2_fast = 20 },
 };
 
+static void
+skl_wa_clkgate(struct drm_i915_private *dev_priv, int pipe, bool enable)
+{
+	if (IS_SKYLAKE(dev_priv))
+		return;
+
+	if (enable)
+		I915_WRITE(CLKGATE_DIS_PSL(pipe),
+			   DUPS1_GATING_DIS | DUPS2_GATING_DIS);
+	else
+		I915_WRITE(CLKGATE_DIS_PSL(pipe),
+			   I915_READ(CLKGATE_DIS_PSL(pipe)) &
+			   ~(DUPS1_GATING_DIS|DUPS2_GATING_DIS));
+}
+
 static bool
 needs_modeset(const struct drm_crtc_state *state)
 {
@@ -3151,6 +3166,9 @@ int skl_check_plane_surface(const struct intel_crtc_state *crtc_state,
 	const struct drm_framebuffer *fb = plane_state->base.fb;
 	unsigned int rotation = plane_state->base.rotation;
 	int ret;
+	struct intel_crtc *intel_crtc = to_intel_crtc(crtc_state->base.crtc);
+	struct drm_i915_private *dev_priv =
+		to_i915(plane_state->base.plane->dev);
 
 	if (rotation & DRM_MODE_REFLECT_X &&
 	    fb->modifier == DRM_FORMAT_MOD_LINEAR) {
@@ -3175,6 +3193,13 @@ int skl_check_plane_surface(const struct intel_crtc_state *crtc_state,
 		ret = skl_check_nv12_aux_surface(plane_state);
 		if (ret)
 			return ret;
+
+		/* Display WA 827 */
+		if (INTEL_GEN(dev_priv) == 9 || IS_CANNONLAKE(dev_priv)) {
+			if (!IS_GEMINILAKE(dev_priv))
+				skl_wa_clkgate(dev_priv,
+					       intel_crtc->pipe, true);
+		}
 	} else if (fb->modifier == I915_FORMAT_MOD_Y_TILED_CCS ||
 		   fb->modifier == I915_FORMAT_MOD_Yf_TILED_CCS) {
 		ret = skl_check_ccs_aux_surface(plane_state);
@@ -5746,6 +5771,12 @@ static void haswell_crtc_disable(struct intel_crtc_state *old_crtc_state,
 		intel_ddi_disable_pipe_clock(intel_crtc->config);
 
 	intel_encoders_post_disable(crtc, old_crtc_state, old_state);
+
+	if (INTEL_GEN(dev_priv) == 9 || IS_CANNONLAKE(dev_priv)) {
+		if (!IS_GEMINILAKE(dev_priv))
+			skl_wa_clkgate(dev_priv,
+				       intel_crtc->pipe, false);
+	}
 }
 
 static void i9xx_pfit_enable(struct intel_crtc *crtc)
-- 
2.7.4