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From 6c4a258ac11941ee18354cb8b2b8b923803f061e Mon Sep 17 00:00:00 2001
From: Eric Yang <Eric.Yang2@amd.com>
Date: Fri, 23 Nov 2018 05:55:20 -0500
Subject: [PATCH 0964/2940] 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>
---
drivers/gpu/drm/amd/display/dc/core/dc_link.c | 18 ++++++++++++++++--
1 file changed, 16 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link.c b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
index 1bebb60ac629..30ab9b7a161c 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
@@ -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;
}
--
2.17.1
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