6.6-stable review patch. If anyone has any objections, please let me know.
------------------
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(<_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,
