From: Imre Deak <imre.deak@intel.com>
Date: Mon, 15 Dec 2025 19:23:49 +0000 (+0200)
Subject: drm/i915/dp: Use the effective data rate for DP compressed BW calculation
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2fb850a6aeb20b6a28c23dbddf1eaa704abb9ce9;p=thirdparty%2Fkernel%2Flinux.git

drm/i915/dp: Use the effective data rate for DP compressed BW calculation

Use intel_dp_effective_data_rate() to calculate the required link BW for
compressed streams on non-UHBR DP-SST links. This ensures that the BW is
calculated the same way for all DP output types and DSC/non-DSC modes,
during mode validation as well as during state computation.

This approach also allows for accounting with BW overhead due to DSC,
FEC being enabled on a link. Acounting for these will be added by
follow-up changes.

Reviewed-by: Luca Coelho <luciano.coelho@intel.com>
Reviewed-by: Vinod Govindapillai <vinod.govindapillai@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Link: https://patch.msgid.link/20251215192357.172201-10-imre.deak@intel.com
---

diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
index 79373b84d30f..a2939843a72a 100644
--- a/drivers/gpu/drm/i915/display/intel_dp.c
+++ b/drivers/gpu/drm/i915/display/intel_dp.c
@@ -2026,15 +2026,19 @@ static bool intel_dp_dsc_supports_format(const struct intel_connector *connector
 	return drm_dp_dsc_sink_supports_format(connector->dp.dsc_dpcd, sink_dsc_format);
 }
 
-static bool is_bw_sufficient_for_dsc_config(int dsc_bpp_x16, u32 link_clock,
-					    u32 lane_count, u32 mode_clock,
-					    enum intel_output_format output_format,
-					    int timeslots)
+static bool is_bw_sufficient_for_dsc_config(struct intel_dp *intel_dp,
+					    int link_clock, int lane_count,
+					    int mode_clock, int mode_hdisplay,
+					    int dsc_slice_count, int link_bpp_x16,
+					    unsigned long bw_overhead_flags)
 {
-	u32 available_bw, required_bw;
+	int available_bw;
+	int required_bw;
 
-	available_bw = (link_clock * lane_count * timeslots * 16)  / 8;
-	required_bw = dsc_bpp_x16 * (intel_dp_mode_to_fec_clock(mode_clock));
+	available_bw = intel_dp_max_link_data_rate(intel_dp, link_clock, lane_count);
+	required_bw = intel_dp_link_required(link_clock, lane_count,
+					     mode_clock, mode_hdisplay,
+					     link_bpp_x16, bw_overhead_flags);
 
 	return available_bw >= required_bw;
 }
@@ -2082,11 +2086,12 @@ static int dsc_compute_link_config(struct intel_dp *intel_dp,
 				if (ret)
 					continue;
 			} else {
-				if (!is_bw_sufficient_for_dsc_config(dsc_bpp_x16, link_rate,
-								     lane_count,
+				if (!is_bw_sufficient_for_dsc_config(intel_dp,
+								     link_rate, lane_count,
 								     adjusted_mode->crtc_clock,
-								     pipe_config->output_format,
-								     timeslots))
+								     adjusted_mode->hdisplay,
+								     pipe_config->dsc.slice_count,
+								     dsc_bpp_x16, 0))
 					continue;
 			}