[Intel-gfx] [PATCH] drm/i915/display: Program pipe A PIPE_MISC_A bit 9 Pixel Extension to 0

[Animesh Manna]

From: Jigar Bhatt <jigar.bhatt at intel.com>

Due to RTL bug FBC cannot be enabled when pipe is programed in Pixel
Extension mode of Zero Extend. This caused 1 bit change in pixel value
in compressed vs uncompressed frame which comes up as a flicker.
WA for D13 is to always used MSB Extend for Pixel extension.

WA: 16015082434

Signed-off-by: Jigar Bhatt <jigar.bhatt at intel.com>
Signed-off-by: Animesh Manna <animesh.manna at intel.com>
---
 drivers/gpu/drm/i915/display/intel_display.c | 4 +++-
 drivers/gpu/drm/i915/i915_reg.h              | 1 +
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_display.c b/drivers/gpu/drm/i915/display/intel_display.c
index 5a386c7c0bc9..7006c1cb09f7 100644
--- a/drivers/gpu/drm/i915/display/intel_display.c
+++ b/drivers/gpu/drm/i915/display/intel_display.c
@@ -3374,8 +3374,10 @@ static void bdw_set_pipe_misc(const struct intel_crtc_state *crtc_state)
 	if (DISPLAY_VER(dev_priv) >= 11 && is_hdr_mode(crtc_state))
 		val |= PIPE_MISC_HDR_MODE_PRECISION;
 
-	if (DISPLAY_VER(dev_priv) >= 12)
+	if (DISPLAY_VER(dev_priv) >= 12) {
 		val |= PIPE_MISC_PIXEL_ROUNDING_TRUNC;
+		val &= ~(PIPEMISC_PIXEL_EXTENSION_ZERO_EXTEND);
+	}
 
 	intel_de_write(dev_priv, PIPE_MISC(crtc->pipe), val);
 }
diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index d22ffd7a32dc..dcad60b5f50e 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -3501,6 +3501,7 @@
 #define   PIPE_MISC_YUV420_MODE_FULL_BLEND	REG_BIT(26) /* glk+ */
 #define   PIPE_MISC_HDR_MODE_PRECISION		REG_BIT(23) /* icl+ */
 #define   PIPE_MISC_OUTPUT_COLORSPACE_YUV	REG_BIT(11)
+#define   PIPEMISC_PIXEL_EXTENSION_ZERO_EXTEND	REG_BIT(9)
 #define   PIPE_MISC_PIXEL_ROUNDING_TRUNC		REG_BIT(8) /* tgl+ */
 /*
  * For Display < 13, Bits 5-7 of PIPE MISC represent DITHER BPC with
-- 
2.29.0