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From 33c8f16adbd0f4c2352beffcbb9c2bc87b618a97 Mon Sep 17 00:00:00 2001
From: Chris Park <Chris.Park@amd.com>
Date: Fri, 10 May 2019 13:34:30 -0400
Subject: [PATCH 2462/2940] drm/amd/display: Move link functions from dc to
dc_link
[Why]
link-specific functions should reside in dc_link.c
[How]
Move them there.
Signed-off-by: Chris Park <Chris.Park@amd.com>
Reviewed-by: Charlene Liu <Charlene.Liu@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
---
drivers/gpu/drm/amd/display/dc/core/dc_link.c | 27 +++++++++++++++++++
1 file changed, 27 insertions(+)
diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
index b43bcdfd0caf..28cb4b3ce7af 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
@@ -3053,6 +3053,33 @@ uint32_t dc_link_bandwidth_kbps(
link_bw_kbps *= 8; /* 8 bits per byte*/
link_bw_kbps *= link_setting->lane_count;
+#ifdef CONFIG_DRM_AMD_DC_DSC_SUPPORT
+ if (link->dpcd_caps.fec_cap.bits.FEC_CAPABLE) {
+ /* Account for FEC overhead.
+ * We have to do it based on caps,
+ * and not based on FEC being set ready,
+ * because FEC is set ready too late in
+ * the process to correctly be picked up
+ * by mode enumeration.
+ *
+ * There's enough zeros at the end of 'kbps'
+ * that make the below operation 100% precise
+ * for our purposes.
+ * 'long long' makes it work even for HDMI 2.1
+ * max bandwidth (and much, much bigger bandwidths
+ * than that, actually).
+ *
+ * NOTE: Reducing link BW by 3% may not be precise
+ * because it may be a stream BT that increases by 3%, and so
+ * 1/1.03 = 0.970873 factor should have been used instead,
+ * but the difference is minimal and is in a safe direction,
+ * which all works well around potential ambiguity of DP 1.4a spec.
+ */
+ long long fec_link_bw_kbps = link_bw_kbps * 970LL;
+ link_bw_kbps = (uint32_t)(fec_link_bw_kbps / 1000LL);
+ }
+#endif
+
return link_bw_kbps;
}
--
2.17.1
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