drm/i915/vrr: Make delayed vblank operational in VRR mode on adl/dg2

On adl/dg2 a chicken bit needs to be set for TRANS_SET_CONTENXT_LATENCY
to take effect in VRR mode. Can't really think of a reason why we'd
ever disable that chicken bit, so let's just always set it.
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230320203352.19515-4-ville.syrjala@linux.intel.comReviewed-by: Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>

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

@@ -173,6 +173,14 @@ void intel_vrr_enable(const struct intel_crtc_state *crtc_state)
 	struct drm_i915_private *dev_priv = to_i915(crtc_state->uapi.crtc->dev);
 	enum transcoder cpu_transcoder = crtc_state->cpu_transcoder;
 
+	/*
+	 * TRANS_SET_CONTEXT_LATENCY with VRR enabled
+	 * requires this chicken bit on ADL/DG2.
+	 */
+	if (DISPLAY_VER(dev_priv) == 13)
+		intel_de_rmw(dev_priv, CHICKEN_TRANS(cpu_transcoder),
+			     0, PIPE_VBLANK_WITH_DELAY);
+
 	if (!crtc_state->vrr.enable)
 		return;
 

drivers/gpu/drm/i915/i915_reg.h

@@ -4560,13 +4560,12 @@
 					    [TRANSCODER_B] = _CHICKEN_TRANS_B, \
 					    [TRANSCODER_C] = _CHICKEN_TRANS_C, \
 					    [TRANSCODER_D] = _CHICKEN_TRANS_D))
-
 #define _MTL_CHICKEN_TRANS_A	0x604e0
 #define _MTL_CHICKEN_TRANS_B	0x614e0
 #define MTL_CHICKEN_TRANS(trans)	_MMIO_TRANS((trans), \
 						    _MTL_CHICKEN_TRANS_A, \
 						    _MTL_CHICKEN_TRANS_B)
-
+#define  PIPE_VBLANK_WITH_DELAY		REG_BIT(31) /* ADL/DG2 */
 #define  HSW_FRAME_START_DELAY_MASK	REG_GENMASK(28, 27)
 #define  HSW_FRAME_START_DELAY(x)	REG_FIELD_PREP(HSW_FRAME_START_DELAY_MASK, x)
 #define  VSC_DATA_SEL_SOFTWARE_CONTROL	REG_BIT(25) /* GLK */