From 52ecd48b8d3f5206049758d95ca5b291397b3209 Mon Sep 17 00:00:00 2001 From: Ankit Nautiyal Date: Fri, 17 Oct 2025 18:05:01 +0530 Subject: [PATCH] drm/i915/dp: Add helper to get min sdp guardband MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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. v2: Correct the lines required for PPS SDP. (Jouni) Bspec: 70151 Signed-off-by: Ankit Nautiyal Reviewed-by: Jouni Högander Link: https://lore.kernel.org/r/20251017123504.2247954-3-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 215ad690ab077..9441ef6852005 100644 --- a/drivers/gpu/drm/i915/display/intel_dp.c +++ b/drivers/gpu/drm/i915/display/intel_dp.c @@ -7002,3 +7002,39 @@ 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 7; + 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 0537be20fe7b9..200a8b267f647 100644 --- a/drivers/gpu/drm/i915/display/intel_dp.h +++ b/drivers/gpu/drm/i915/display/intel_dp.h @@ -223,5 +223,7 @@ 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__ */ -- 2.47.3