[PATCH 4/6] drm/i915/dp: Add helper to get min sdp guardband

[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.

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 | 36 +++++++++++++++++++++++++
 drivers/gpu/drm/i915/display/intel_dp.h |  2 ++
 2 files changed, 38 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 7059d55687cf..3f2c319e3d6f 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -6990,3 +6990,39 @@ int intel_dp_compute_config_late(struct intel_encoder *encoder,
 
 	return 0;
 }
+
+static
+int intel_dp_get_lines_for_sdp(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_sdp_min_guardband(const struct intel_crtc_state *crtc_state,
+			       bool assume_all_enabled)
+{
+	int sdp_guardband = 0;
+
+	if (assume_all_enabled ||
+	    crtc_state->infoframes.enable &
+	    intel_hdmi_infoframe_enable(HDMI_PACKET_TYPE_GAMUT_METADATA))
+		sdp_guardband = max(sdp_guardband,
+				    intel_dp_get_lines_for_sdp(HDMI_PACKET_TYPE_GAMUT_METADATA));
+
+	if (assume_all_enabled ||
+	    crtc_state->dsc.compression_enable)
+		sdp_guardband = max(sdp_guardband, intel_dp_get_lines_for_sdp(DP_SDP_PPS));
+
+	return sdp_guardband;
+}
diff --git a/drivers/gpu/drm/i915/display/intel_dp.h b/drivers/gpu/drm/i915/display/intel_dp.h
index 281ced3a3b39..7ee5aeb28fe2 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.h
+++ b/drivers/gpu/drm/i915/display/intel_dp.h
@@ -221,5 +221,7 @@ bool intel_dp_in_hdr_mode(const struct drm_connector_state *conn_state);
 int intel_dp_compute_config_late(struct intel_encoder *encoder,
 				 struct intel_crtc_state *crtc_state,
 				 struct drm_connector_state *conn_state);
+int intel_dp_sdp_min_guardband(const struct intel_crtc_state *crtc_state,
+			       bool assume_all_enabled);
 
 #endif /* __INTEL_DP_H__ */
-- 
2.45.2