drm/i915: Set up PIPE_MISC truncate bit on tgl+

Looks like the pipe rounding mode bit has moved from PIPE_CHICKEN to
PIPE_MISC on tgl. Frob the new location.

Bspec does still document the old bits as well, so I left the code
for them as is until we get clarification from the hw folks on
whether the old bits still do something useful.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200226163054.9509-1-ville.syrjala@linux.intel.comReviewed-by: José Roberto de Souza <jose.souza@intel.com>

drivers/gpu/drm/i915/display/intel_display.c

@@ -10138,6 +10138,9 @@ static void bdw_set_pipemisc(const struct intel_crtc_state *crtc_state)
 					   BIT(PLANE_CURSOR))) == 0)
 		val |= PIPEMISC_HDR_MODE_PRECISION;
 
+	if (INTEL_GEN(dev_priv) >= 12)
+		val |= PIPEMISC_PIXEL_ROUNDING_TRUNC;
+
 	intel_de_write(dev_priv, PIPEMISC(crtc->pipe), val);
 }
 

drivers/gpu/drm/i915/i915_reg.h

@@ -5879,6 +5879,7 @@ enum {
 #define   PIPEMISC_YUV420_MODE_FULL_BLEND (1 << 26) /* glk+ */
 #define   PIPEMISC_HDR_MODE_PRECISION	(1 << 23) /* icl+ */
 #define   PIPEMISC_OUTPUT_COLORSPACE_YUV  (1 << 11)
+#define   PIPEMISC_PIXEL_ROUNDING_TRUNC	REG_BIT(8) /* tgl+ */
 #define   PIPEMISC_DITHER_BPC_MASK	(7 << 5)
 #define   PIPEMISC_DITHER_8_BPC		(0 << 5)
 #define   PIPEMISC_DITHER_10_BPC	(1 << 5)