drm/i915/mtl+: Disable DP/DSC SF insertion at EOL WA

Disable the workaround inserting an SF symbol between the last DSC EOC
symbol and the subsequent BS symbol. The WA is enabled by default -
based on the register's reset value - and Bspec requires disabling it
explicitly. Bspec doesn't provide an actual WA ID for this.

Bspec: 50054, 65448, 68849
Reviewed-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240129175533.904590-6-imre.deak@intel.com

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

@@ -436,6 +436,15 @@ void intel_enable_transcoder(const struct intel_crtc_state *new_crtc_state)
 		intel_de_rmw(dev_priv, PIPE_ARB_CTL(pipe),
 			     0, PIPE_ARB_USE_PROG_SLOTS);
 
+	if (DISPLAY_VER(dev_priv) >= 14) {
+		u32 clear = DP_DSC_INSERT_SF_AT_EOL_WA;
+		u32 set = 0;
+
+		intel_de_rmw(dev_priv,
+			     hsw_chicken_trans_reg(dev_priv, cpu_transcoder),
+			     clear, set);
+	}
+
 	val = intel_de_read(dev_priv, TRANSCONF(cpu_transcoder));
 	if (val & TRANSCONF_ENABLE) {
 		/* we keep both pipes enabled on 830 */

drivers/gpu/drm/i915/i915_reg.h

@@ -4629,6 +4629,7 @@
 #define   DDIE_TRAINING_OVERRIDE_VALUE	REG_BIT(16) /* CHICKEN_TRANS_A only */
 #define   PSR2_ADD_VERTICAL_LINE_COUNT	REG_BIT(15)
 #define   PSR2_VSC_ENABLE_PROG_HEADER	REG_BIT(12)
+#define   DP_DSC_INSERT_SF_AT_EOL_WA	REG_BIT(4)
 
 #define DISP_ARB_CTL	_MMIO(0x45000)
 #define   DISP_FBC_MEMORY_WAKE		REG_BIT(31)