[Intel-gfx] [PATCH v1 1/1] 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   | 15 +++++++++++++++
 drivers/gpu/drm/i915/display/intel_display.c |  7 ++++++-
 drivers/gpu/drm/i915/i915_reg.h              |  3 ++-
 3 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/i915/display/intel_color.c b/drivers/gpu/drm/i915/display/intel_color.c
index dab892d2251b..4ad5bd849695 100644
--- a/drivers/gpu/drm/i915/display/intel_color.c
+++ b/drivers/gpu/drm/i915/display/intel_color.c
@@ -1605,6 +1605,20 @@ static u32 icl_csc_mode(const struct intel_crtc_state *crtc_state)
 	return csc_mode;
 }
 
+static u32 dither_after_cc1_12bpc(const struct intel_crtc_state *crtc_state)
+{
+	u32 gamma_mode = crtc_state->gamma_mode;
+	struct drm_i915_private *i915 = to_i915(crtc_state->uapi.crtc->dev);
+
+	if (DISPLAY_VER(i915) >= 13) {
+		if (!crtc_state->dither_force_disable &&
+		    (crtc_state->pipe_bpp == 36))
+			gamma_mode |= GAMMA_MODE_DITHER_AFTER_CC1;
+	}
+
+	return gamma_mode;
+}
+
 static int icl_color_check(struct intel_crtc_state *crtc_state)
 {
 	int ret;
@@ -1615,6 +1629,7 @@ static int icl_color_check(struct intel_crtc_state *crtc_state)
 
 	crtc_state->gamma_mode = icl_gamma_mode(crtc_state);
 
+	crtc_state->gamma_mode = dither_after_cc1_12bpc(crtc_state);
 	crtc_state->csc_mode = icl_csc_mode(crtc_state);
 
 	crtc_state->preload_luts = intel_can_preload_luts(crtc_state);
diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 0bb2e582c87f..1a658bdaeab6 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -5741,7 +5741,12 @@ 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
+	 */
+
+	if (crtc_state->dither && (crtc_state->pipe_bpp != 36))
 		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 4dbe79009c0e..5700097475c0 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -6155,7 +6155,7 @@ enum {
 #define   PIPEMISC_DITHER_8_BPC		(0 << 5)
 #define   PIPEMISC_DITHER_10_BPC	(1 << 5)
 #define   PIPEMISC_DITHER_6_BPC		(2 << 5)
-#define   PIPEMISC_DITHER_12_BPC	(3 << 5)
+#define   PIPEMISC_DITHER_12_BPC	(4 << 5)
 #define   PIPEMISC_DITHER_ENABLE	(1 << 4)
 #define   PIPEMISC_DITHER_TYPE_MASK	(3 << 2)
 #define   PIPEMISC_DITHER_TYPE_SP	(0 << 2)
@@ -7726,6 +7726,7 @@ enum {
 #define  GAMMA_MODE_MODE_12BIT	(2 << 0)
 #define  GAMMA_MODE_MODE_SPLIT	(3 << 0) /* ivb-bdw */
 #define  GAMMA_MODE_MODE_12BIT_MULTI_SEGMENTED	(3 << 0) /* icl + */
+#define  GAMMA_MODE_DITHER_AFTER_CC1 (1 << 26)
 
 /* DMC */
 #define DMC_PROGRAM(i)		_MMIO(0x80000 + (i) * 4)
-- 
2.29.2