[PATCH 6.18 116/752] drm/amd/display: Correct FIXED_VS Link Rate Toggle Condition

Sasha Levin
2026-02-28T17:49:46Z

From: Jing Zhou <Jing.Zhou@amd.com>

[ Upstream commit 531fe6e0fee85a1bdb5b8223a706fff654ed0a61 ]

[WHY&HOW]
The condition is only perform toggle if FIXED_VS LTTPR reports
no IEEE OUI.
The literal "\x0,\x0,\x0" contains commas changes the
bytes being compared to {0x00,0x2C,0X00}.
The correct literal should be "\x00\x00\x00" without commas.

Reviewed-by: Charlene Liu <charlene.liu@amd.com>
Reviewed-by: Wenjing Liu <wenjing.liu@amd.com>
Signed-off-by: Jing Zhou <Jing.Zhou@amd.com>
Signed-off-by: Roman Li <roman.li@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
.../dc/link/protocols/link_dp_training_fixed_vs_pe_retimer.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git 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
index ce174ce5579c0..6a7c4a59ff4c7 100644
--- 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
@@ -271,7 +271,7 @@ enum link_training_result dp_perform_fixed_vs_pe_training_sequence(
rate = get_dpcd_link_rate(&lt_settings->link_settings);

// Only perform toggle if FIXED_VS LTTPR reports no IEEE OUI
- if (memcmp("\x0,\x0,\x0", &link->dpcd_caps.lttpr_caps.lttpr_ieee_oui[0], 3) == 0) {
+ if (memcmp("\x00\x00\x00", &link->dpcd_caps.lttpr_caps.lttpr_ieee_oui[0], 3) == 0) {
/* Vendor specific: Toggle link rate */
toggle_rate = (rate == 0x6) ? 0xA : 0x6;

--
2.51.0