[PATCH 3/6] drm/i915/dp: Add SDP latency computation helper

[Ankit Nautiyal <ankit.k.nautiyal@intel.com>]

Add a helper to compute vblank time needed for transmitting specific
DisplayPort SDPs like PPS, GAMUT_METADATA, and VSC_EXT. Latency is
based on line count per packet type and current line time.

This will be used to ensure adequate guardband when features like DSC/HDR
are enabled.

Bspec: 70151
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal@intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp.c | 33 +++++++++++++++++++++++++
 drivers/gpu/drm/i915/display/intel_dp.h |  1 +
 2 files changed, 34 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index e481ff4c4959..54d31d02ba50 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -6988,3 +6988,36 @@ void intel_dp_compute_config_late(struct intel_encoder *encoder,
 
 	intel_psr_compute_config_late(intel_dp, crtc_state);
 }
+
+static
+int intel_dp_get_sdp_latency(u32 type)
+{
+	switch (type) {
+	case DP_SDP_VSC_EXT_VESA:
+	case DP_SDP_VSC_EXT_CEA:
+		return 10;
+	case HDMI_PACKET_TYPE_GAMUT_METADATA:
+		return 8;
+	case DP_SDP_PPS:
+		return 6;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+int intel_dp_compute_sdp_latency(const struct intel_crtc_state *crtc_state)
+{
+	int sdp_latency = 0;
+
+	if (crtc_state->infoframes.enable &
+	    intel_hdmi_infoframe_enable(HDMI_PACKET_TYPE_GAMUT_METADATA))
+		sdp_latency = max(sdp_latency,
+				  intel_dp_get_sdp_latency(HDMI_PACKET_TYPE_GAMUT_METADATA));
+
+	if (crtc_state->dsc.compression_enable)
+		sdp_latency = max(sdp_latency, intel_dp_get_sdp_latency(DP_SDP_PPS));
+
+	return sdp_latency;
+}
diff --git a/drivers/gpu/drm/i915/display/intel_dp.h b/drivers/gpu/drm/i915/display/intel_dp.h
index 0d9573ca44cb..27089cef86d8 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.h
+++ b/drivers/gpu/drm/i915/display/intel_dp.h
@@ -221,5 +221,6 @@ bool intel_dp_in_hdr_mode(const struct drm_connector_state *conn_state);
 void intel_dp_compute_config_late(struct intel_encoder *encoder,
 				  struct intel_crtc_state *crtc_state,
 				  struct drm_connector_state *conn_state);
+int intel_dp_compute_sdp_latency(const struct intel_crtc_state *crtc_state);
 
 #endif /* __INTEL_DP_H__ */
-- 
2.45.2