[Intel-gfx] [PATCH] drm/i915/xelpd: Enabling dithering after the CC1

[Nischal Varide]

If the panel is 12bpc then Dithering is not enabled in the Legacy
dithering block , instead its Enabled after the C1 CC1 pipe post
color space conversion.For a 6bpc pannel Dithering is enabled in
Legacy block.

Signed-off-by: Nischal Varide <nischal.varide at intel.com>
---
 drivers/gpu/drm/i915/display/intel_color.c   |  7 +++++++
 drivers/gpu/drm/i915/display/intel_display.c | 11 ++++++++++-
 drivers/gpu/drm/i915/i915_reg.h              |  1 +
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_color.c b/drivers/gpu/drm/i915/display/intel_color.c
index dab892d2251b..c7af583200c4 100644
--- a/drivers/gpu/drm/i915/display/intel_color.c
+++ b/drivers/gpu/drm/i915/display/intel_color.c
@@ -1574,6 +1574,7 @@ static int glk_color_check(struct intel_crtc_state *crtc_state)
 static u32 icl_gamma_mode(const struct intel_crtc_state *crtc_state)
 {
 	u32 gamma_mode = 0;
+	struct drm_i915_private *i915 = to_i915(crtc_state->uapi.crtc->dev);
 
 	if (crtc_state->hw.degamma_lut)
 		gamma_mode |= PRE_CSC_GAMMA_ENABLE;
@@ -1588,6 +1589,12 @@ static u32 icl_gamma_mode(const struct intel_crtc_state *crtc_state)
 	else
 		gamma_mode |= GAMMA_MODE_MODE_12BIT_MULTI_SEGMENTED;
 
+	if (DISPLAY_VER(i915) >= 13) {
+		if (!crtc_state->dither_force_disable &&
+				(crtc_state->pipe_bpp == 36))
+			gamma_mode |= POST_CC1_DITHER_ENABLE;
+	}
+
 	return gamma_mode;
 }
 
diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 362bff9beb5c..3a7feb246745 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -5762,7 +5762,16 @@ static void bdw_set_pipemisc(const struct intel_crtc_state *crtc_state)
 		break;
 	}
 
-	if (crtc_state->dither)
+	/*
+	 * If 12bpc panel then, Enables dithering after the CC1 pipe
+	 * post color space conversion and not here for display_ver
+	 * greater than or equal to thirteen.
+	 */
+
+	if (crtc_state->dither && (crtc_state->pipe_bpp != 36))
+		val |= PIPEMISC_DITHER_ENABLE | PIPEMISC_DITHER_TYPE_SP;
+
+	if (crtc_state->dither && (crtc_state->pipe_bpp == 36) && (DISPLAY_VER(dev_priv) < 13))
 		val |= PIPEMISC_DITHER_ENABLE | PIPEMISC_DITHER_TYPE_SP;
 
 	if (crtc_state->output_format == INTEL_OUTPUT_FORMAT_YCBCR420 ||
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index e915ec034c98..33dba13fa94d 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -7743,6 +7743,7 @@ enum {
 #define GAMMA_MODE(pipe) _MMIO_PIPE(pipe, _GAMMA_MODE_A, _GAMMA_MODE_B)
 #define  PRE_CSC_GAMMA_ENABLE	(1 << 31)
 #define  POST_CSC_GAMMA_ENABLE	(1 << 30)
+#define  POST_CC1_DITHER_ENABLE (1 << 26)
 #define  GAMMA_MODE_MODE_MASK	(3 << 0)
 #define  GAMMA_MODE_MODE_8BIT	(0 << 0)
 #define  GAMMA_MODE_MODE_10BIT	(1 << 0)
-- 
2.29.2