[PATCH 06/15] drm/i915/dp: Add SDP latency computation helper

[Ankit Nautiyal]

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.

Used to ensure adequate vblank when features like DSC/HDR are enabled.

Bspec: 70151
Signed-off-by: Ankit Nautiyal <ankit.k.nautiyal at intel.com>
---
 drivers/gpu/drm/i915/display/intel_dp.c | 47 +++++++++++++++++++++++++
 drivers/gpu/drm/i915/display/intel_dp.h |  1 +
 2 files changed, 48 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 54d88f24b689..a7ecc8ad67f2 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -6807,3 +6807,50 @@ void intel_dp_mst_resume(struct intel_display *display)
 		}
 	}
 }
+
+static
+int intel_dp_get_sdp_latency(u32 type, int linetime_us)
+{
+	int lines;
+
+	switch (type) {
+	case DP_SDP_VSC_EXT_VESA:
+	case DP_SDP_VSC_EXT_CEA:
+		lines = 10;
+		break;
+	case HDMI_PACKET_TYPE_GAMUT_METADATA:
+		lines = 8;
+		break;
+	case DP_SDP_PPS:
+		lines = 6;
+		break;
+	default:
+		lines = 0;
+		break;
+	}
+
+	return lines * linetime_us;
+}
+
+int intel_dp_compute_sdp_latency(struct intel_crtc_state *crtc_state,
+				 bool assume_all_enabled)
+{
+	const struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;
+	int sdp_latency = 0;
+	int linetime_us;
+
+	linetime_us = DIV_ROUND_UP(adjusted_mode->crtc_htotal * 1000,
+				   adjusted_mode->crtc_clock);
+	if (assume_all_enabled ||
+	    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,
+							   linetime_us));
+
+	if (assume_all_enabled || crtc_state->dsc.compression_enable)
+		sdp_latency = max(sdp_latency,
+				  intel_dp_get_sdp_latency(DP_SDP_PPS, linetime_us));
+
+	return sdp_latency;
+}
diff --git a/drivers/gpu/drm/i915/display/intel_dp.h b/drivers/gpu/drm/i915/display/intel_dp.h
index 0657f5681196..994994d68475 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.h
+++ b/drivers/gpu/drm/i915/display/intel_dp.h
@@ -214,5 +214,6 @@ int intel_dp_compute_min_hblank(struct intel_crtc_state *crtc_state,
 
 int intel_dp_dsc_bpp_step_x16(const struct intel_connector *connector);
 void intel_dp_dpcd_set_probe(struct intel_dp *intel_dp, bool force_on_external);
+int intel_dp_compute_sdp_latency(struct intel_crtc_state *crtc_state, bool assume_all_enabled);
 
 #endif /* __INTEL_DP_H__ */
-- 
2.45.2