From f229592ed9cd0bf93d4396de52addc0243346d06 Mon Sep 17 00:00:00 2001
From: Jani Nikula <jani.nikula@intel.com>
Date: Thu, 9 Sep 2021 15:51:53 +0300
Subject: drm/dp: add DP 2.0 UHBR link rate and bw code conversions
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Git-commit: 054ce0bce22eeb714c6cc3808869a326d0611792
Patch-mainline: v5.16-rc1
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225

The bw code equals link_rate / 0.27 Gbps only for 8b/10b link
rates. Handle DP 2.0 UHBR rates as special cases, though this is not
pretty.

Cc: dri-devel@lists.freedesktop.org
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Maxime Ripard <mripard@kernel.org>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/cab4edda8834d6b4db610fabb5e1f1f18ae33c2c.1631191763.git.jani.nikula@intel.com
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
 drivers/gpu/drm/drm_dp_helper.c | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 6d0f2c447f3b..9b2a2961fca8 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -207,15 +207,33 @@ EXPORT_SYMBOL(drm_dp_lttpr_link_train_channel_eq_delay);
 
 u8 drm_dp_link_rate_to_bw_code(int link_rate)
 {
-	/* Spec says link_bw = link_rate / 0.27Gbps */
-	return link_rate / 27000;
+	switch (link_rate) {
+	case 1000000:
+		return DP_LINK_BW_10;
+	case 1350000:
+		return DP_LINK_BW_13_5;
+	case 2000000:
+		return DP_LINK_BW_20;
+	default:
+		/* Spec says link_bw = link_rate / 0.27Gbps */
+		return link_rate / 27000;
+	}
 }
 EXPORT_SYMBOL(drm_dp_link_rate_to_bw_code);
 
 int drm_dp_bw_code_to_link_rate(u8 link_bw)
 {
-	/* Spec says link_rate = link_bw * 0.27Gbps */
-	return link_bw * 27000;
+	switch (link_bw) {
+	case DP_LINK_BW_10:
+		return 1000000;
+	case DP_LINK_BW_13_5:
+		return 1350000;
+	case DP_LINK_BW_20:
+		return 2000000;
+	default:
+		/* Spec says link_rate = link_bw * 0.27Gbps */
+		return link_bw * 27000;
+	}
 }
 EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate);
 
-- 
2.38.1