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drm/amd/display: Don't skip link training for empty dongle 

[Why]
Skipping initial link training will result in no verified link cap for
mode enumeration. Some versions of the BIOS seem to have PHY programming
sequence issue as well if initial link training is skipped, resulting in
a softlock in BIOS command table.

[How]
Identify the empty dongle hotplug case, and still do initial link
training.

Signed-off-by: Eric Yang <Eric.Yang2@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Eric Yang 2018-11-23 05:55:20 -05:00 committed by Alex Deucher
parent 0a6414e75d
commit 80adaebd2d
1 changed files with 16 additions and 2 deletions
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18
drivers/gpu/drm/amd/display/dc/core/dc_link.c
View File

@ -706,12 +706,26 @@ bool dc_link_detect(struct dc_link *link, enum dc_detect_reason reason)
if (memcmp(&link->dpcd_caps, &prev_dpcd_caps, sizeof(struct dpcd_caps)))
same_dpcd = false;
}
/* Active dongle downstream unplug */
/* Active dongle plug in without display or downstream unplug*/
if (link->type == dc_connection_active_dongle
&& link->dpcd_caps.sink_count.
bits.SINK_COUNT == 0) {
if (prev_sink != NULL)
if (prev_sink != NULL) {
/* Downstream unplug */
dc_sink_release(prev_sink);
} else {
/* Empty dongle plug in */
for (i = 0; i < LINK_TRAINING_MAX_VERIFY_RETRY; i++) {
int fail_count = 0;
dp_verify_link_cap(link,
&link->reported_link_cap,
&fail_count);
if (fail_count == 0)
break;
}
}
return true;
}