[Intel-gfx] [PATCH v3 8/9] drm/i915/display/vrr: Set IGNORE_MSA_PAR state in DP Sink

[Manasi Navare]

If VRR is enabled, the sink should ignore MSA parameters
and regenerate incoming video stream without depending
on these parameters. Hence set the MSA_TIMING_PAR_IGNORE_EN
bit if VRR is enabled.
Reset this bit on VRR disable.

Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Cc: Jani Nikula <jani.nikula at linux.intel.com>
Signed-off-by: Manasi Navare <manasi.d.navare at intel.com>
---
 drivers/gpu/drm/i915/display/intel_ddi.c | 25 ++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_ddi.c b/drivers/gpu/drm/i915/display/intel_ddi.c
index 07fb7296c8c7..7db49abd5973 100644
--- a/drivers/gpu/drm/i915/display/intel_ddi.c
+++ b/drivers/gpu/drm/i915/display/intel_ddi.c
@@ -3486,6 +3486,22 @@ i915_reg_t dp_tp_status_reg(struct intel_encoder *encoder,
 		return DP_TP_STATUS(encoder->port);
 }
 
+static void intel_dp_sink_set_msa_timing_par_ignore_state(struct intel_dp *intel_dp,
+							  const struct intel_crtc_state *crtc_state,
+							  bool enable)
+{
+	struct drm_i915_private *i915 = dp_to_i915(intel_dp);
+
+	if (!crtc_state->vrr.enable)
+		return;
+
+	if (drm_dp_dpcd_writeb(&intel_dp->aux, DP_DOWNSPREAD_CTRL,
+			       enable ? DP_MSA_TIMING_PAR_IGNORE_EN : 0) <= 0)
+		drm_dbg_kms(&i915->drm,
+			    "Failed to set MSA_TIMING_PAR_IGNORE %s in the sink\n",
+			    enable ? "enable" : "disable");
+}
+
 static void intel_dp_sink_set_fec_ready(struct intel_dp *intel_dp,
 					const struct intel_crtc_state *crtc_state)
 {
@@ -3659,6 +3675,12 @@ static void tgl_ddi_pre_enable_dp(struct intel_atomic_state *state,
 	 */
 	intel_dp_sink_set_fec_ready(intel_dp, crtc_state);
 
+	/*
+	 * Sink device should ignore MSA parameters and regenerate
+	 * incoming video stream in case of VRR/Adaptive Sync
+	 */
+	intel_dp_sink_set_msa_timing_par_ignore_state(intel_dp, crtc_state, true);
+
 	/*
 	 * 7.i Follow DisplayPort specification training sequence (see notes for
 	 *     failure handling)
@@ -4286,6 +4308,9 @@ static void intel_disable_ddi_dp(struct intel_atomic_state *state,
 	/* Disable the decompression in DP Sink */
 	intel_dp_sink_set_decompression_state(intel_dp, old_crtc_state,
 					      false);
+	/* Disable Ignore_MSA bit in DP Sink */
+	intel_dp_sink_set_msa_timing_par_ignore_state(intel_dp, old_crtc_state,
+						      false);
 }
 
 static void intel_disable_ddi_hdmi(struct intel_atomic_state *state,
-- 
2.19.1