Patch "drm/amd/display: force toggle rate wa for first link training for a retimer" has been added to the 6.6-stable tree

[<gregkh@xxxxxxxxxxxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    drm/amd/display: force toggle rate wa for first link training for a retimer

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     drm-amd-display-force-toggle-rate-wa-for-first-link-training-for-a-retimer.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From eb28018943fed7639dfea1c9ec9c756ec692b99a Mon Sep 17 00:00:00 2001
From: Zhongwei <zhongwei.zhang@xxxxxxx>
Date: Wed, 8 Nov 2023 16:34:36 +0800
Subject: drm/amd/display: force toggle rate wa for first link training for a retimer

From: Zhongwei <zhongwei.zhang@xxxxxxx>

commit eb28018943fed7639dfea1c9ec9c756ec692b99a upstream.

[WHY]
Handover from DMUB to driver does not perform link rate toggle.
It might cause link training failure for boot up.

[HOW]
Force toggle rate wa for first link train.
link->vendor_specific_lttpr_link_rate_wa should be zero then.

Cc: stable@xxxxxxxxxxxxxxx # 6.1+
Reviewed-by: Michael Strauss <michael.strauss@xxxxxxx>
Acked-by: Hamza Mahfooz <hamza.mahfooz@xxxxxxx>
Signed-off-by: Zhongwei <zhongwei.zhang@xxxxxxx>
Signed-off-by: Alex Deucher <alexander.deucher@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training_fixed_vs_pe_retimer.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training_fixed_vs_pe_retimer.c
+++ b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training_fixed_vs_pe_retimer.c
@@ -115,7 +115,7 @@ static enum link_training_result perform
 		lt_settings->cr_pattern_time = 16000;
 
 	/* Fixed VS/PE specific: Toggle link rate */
-	apply_toggle_rate_wa = (link->vendor_specific_lttpr_link_rate_wa == target_rate);
+	apply_toggle_rate_wa = ((link->vendor_specific_lttpr_link_rate_wa == target_rate) || (link->vendor_specific_lttpr_link_rate_wa == 0));
 	target_rate = get_dpcd_link_rate(&lt_settings->link_settings);
 	toggle_rate = (target_rate == 0x6) ? 0xA : 0x6;
 
@@ -271,7 +271,7 @@ enum link_training_result dp_perform_fix
 	/* Vendor specific: Toggle link rate */
 	toggle_rate = (rate == 0x6) ? 0xA : 0x6;
 
-	if (link->vendor_specific_lttpr_link_rate_wa == rate) {
+	if (link->vendor_specific_lttpr_link_rate_wa == rate || link->vendor_specific_lttpr_link_rate_wa == 0) {
 		core_link_write_dpcd(
 				link,
 				DP_LINK_BW_SET,
@@ -617,7 +617,7 @@ enum link_training_result dp_perform_fix
 	/* Vendor specific: Toggle link rate */
 	toggle_rate = (rate == 0x6) ? 0xA : 0x6;
 
-	if (link->vendor_specific_lttpr_link_rate_wa == rate) {
+	if (link->vendor_specific_lttpr_link_rate_wa == rate || link->vendor_specific_lttpr_link_rate_wa == 0) {
 		core_link_write_dpcd(
 				link,
 				DP_LINK_BW_SET,


Patches currently in stable-queue which might be from zhongwei.zhang@xxxxxxx are

queue-6.6/drm-amd-display-force-toggle-rate-wa-for-first-link-training-for-a-retimer.patch