On 10/17/2025 4:20 PM, Hogander, Jouni wrote:
On Fri, 2025-10-17 at 10:31 +0530, Ankit Nautiyal wrote:
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 <[email protected]>
---
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;
I found value 7 in the Bspec you are referring in commit message?
Hmm this indeed is 7, seems I misread the spec. Thanks for catching this!
Regards,
Ankit
BR,
Jouni Högander
+ 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__ */
