From: Michael Strauss <michael.strauss@xxxxxxx>
[WHY]
Some sinks are observed to return invalid LTTPR revision and/or invalid
LTTPR link rate capabilities.
[HOW]
Assume any LTTPR which reports invalid max link rate supports HBR3.
Don't validate LTTPR DPCD revision in dp_is_lttpr_present check.
Reviewed-by: George Shen <george.shen@xxxxxxx>
Reviewed-by: Wenjing Liu <wenjing.liu@xxxxxxx>
Acked-by: Zaeem Mohamed <zaeem.mohamed@xxxxxxx>
Signed-off-by: Michael Strauss <michael.strauss@xxxxxxx>
---
.../dc/link/protocols/link_dp_capability.c | 19 ++++++++++++++++---
1 file changed, 16 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c
index 964abccebdc6..1ff9876e3ca3 100644
--- a/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c
+++ b/drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c
@@ -363,10 +363,10 @@ bool dp_is_128b_132b_signal(struct pipe_ctx *pipe_ctx)
bool dp_is_lttpr_present(struct dc_link *link)
{
+ /* Some sink devices report invalid LTTPR revision, so don't validate against that cap */
return (dp_parse_lttpr_repeater_count(link->dpcd_caps.lttpr_caps.phy_repeater_cnt) != 0 &&
link->dpcd_caps.lttpr_caps.max_lane_count > 0 &&
- link->dpcd_caps.lttpr_caps.max_lane_count <= 4 &&
- link->dpcd_caps.lttpr_caps.revision.raw >= 0x14);
+ link->dpcd_caps.lttpr_caps.max_lane_count <= 4);
}
/* in DP compliance test, DPR-120 may have
@@ -399,7 +399,20 @@ static enum dc_link_rate get_link_rate_from_max_link_bw(
static enum dc_link_rate get_lttpr_max_link_rate(struct dc_link *link)
{
- enum dc_link_rate lttpr_max_link_rate = link->dpcd_caps.lttpr_caps.max_link_rate;
+
+ enum dc_link_rate lttpr_max_link_rate = LINK_RATE_UNKNOWN;
+
+ switch (link->dpcd_caps.lttpr_caps.max_link_rate) {
+ case LINK_RATE_LOW:
+ case LINK_RATE_HIGH:
+ case LINK_RATE_HIGH2:
+ case LINK_RATE_HIGH3:
+ lttpr_max_link_rate = link->dpcd_caps.lttpr_caps.max_link_rate;
+ break;
+ default:
+ // Assume all LTTPRs support up to HBR3 to improve misbehaving sink interop
+ lttpr_max_link_rate = LINK_RATE_HIGH3;
+ }
if (link->dpcd_caps.lttpr_caps.supported_128b_132b_rates.bits.UHBR20)
lttpr_max_link_rate = LINK_RATE_UHBR20;
--
2.34.1
