From: Wesley Chalmers Wesley.Chalmers@amd.com
[ Upstream commit 53c81fc7875bc2dca358485dac3999e14ec91a00 ]
[WHY] Some panels return a link rate of 0 (unknown) in DPCD 0. In this case, an appropriate mode cannot be set, and certain panels will show corruption as they are forced to use a mode they do not support.
[HOW] Read DPCD 10 in the case where supported link rate from DPCD 0 is unknown, and pass that value on to the reported link rate. This re-introduces behaviour present in previous versions that appears to have been accidentally removed.
Signed-off-by: Wesley Chalmers Wesley.Chalmers@amd.com Reviewed-by: Anthony Koo Anthony.Koo@amd.com Acked-by: Bhawanpreet Lakha Bhawanpreet.Lakha@amd.com Signed-off-by: Alex Deucher alexander.deucher@amd.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c index 1ee544a32ebb..253311864cdd 100644 --- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c +++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c @@ -1624,8 +1624,7 @@ static bool decide_edp_link_settings(struct dc_link *link, struct dc_link_settin uint32_t link_bw;
if (link->dpcd_caps.dpcd_rev.raw < DPCD_REV_14 || - link->dpcd_caps.edp_supported_link_rates_count == 0 || - link->dc->config.optimize_edp_link_rate == false) { + link->dpcd_caps.edp_supported_link_rates_count == 0) { *link_setting = link->verified_link_cap; return true; } @@ -2597,7 +2596,8 @@ void detect_edp_sink_caps(struct dc_link *link) memset(supported_link_rates, 0, sizeof(supported_link_rates));
if (link->dpcd_caps.dpcd_rev.raw >= DPCD_REV_14 && - link->dc->config.optimize_edp_link_rate) { + (link->dc->config.optimize_edp_link_rate || + link->reported_link_cap.link_rate == LINK_RATE_UNKNOWN)) { // Read DPCD 00010h - 0001Fh 16 bytes at one shot core_link_read_dpcd(link, DP_SUPPORTED_LINK_RATES, supported_link_rates, sizeof(supported_link_rates)); @@ -2612,6 +2612,9 @@ void detect_edp_sink_caps(struct dc_link *link) link_rate = linkRateInKHzToLinkRateMultiplier(link_rate_in_khz); link->dpcd_caps.edp_supported_link_rates[link->dpcd_caps.edp_supported_link_rates_count] = link_rate; link->dpcd_caps.edp_supported_link_rates_count++; + + if (link->reported_link_cap.link_rate < link_rate) + link->reported_link_cap.link_rate = link_rate; } } }