[PATCH 1/2] drm/i915/xelpd: Enabling dithering after the CC1

[Bhanuprakash Modem]

From: Nischal Varide <nischal.varide at intel.com>

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>
Signed-off-by: Bhanuprakash Modem <bhanuprakash.modem at intel.com>
---
 drivers/gpu/drm/i915/display/intel_color.c   | 7 +++++++
 drivers/gpu/drm/i915/display/intel_display.c | 3 ++-
 drivers/gpu/drm/i915/i915_reg.h              | 1 +
 3 files changed, 10 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 caf0414e0b50..0f29bf4a8472 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -8085,7 +8085,8 @@ intel_modeset_pipe_config(struct intel_atomic_state *state,
 	 * test requesting 6bpc video pattern.
 	 */
 	pipe_config->dither = (pipe_config->pipe_bpp == 6*3) &&
-		!pipe_config->dither_force_disable;
+		!pipe_config->dither_force_disable &&
+		!(pipe_config->gamma_mode & POST_CC1_DITHER_ENABLE);
 	drm_dbg_kms(&i915->drm,
 		    "hw max bpp: %i, pipe bpp: %i, dithering: %i\n",
 		    base_bpp, pipe_config->pipe_bpp, pipe_config->dither);
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 24307c49085f..35e9cfad7495 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)
-- 
2.20.1