From: Ilya <Ilya.Bakoulin@xxxxxxx>
[Why]
Hotplugging the VGA side of some DP/VGA adapters caused the display to
light up with the wrong (non-native) resolution.
This is caused by the adapter misbehaving by reporting the wrong number
of downstream ports when the VGA side is unplugged (reports 1 instead of
0), but only if the SINK_COUNT DPCD register is read more than once.
[How]
To work around the adapter behavior, remove the sink if link is
detected, but EDID cannot be read.
Reviewed-by: Wenjing Liu <Wenjing.Liu@xxxxxxx>
Acked-by: Solomon Chiu <solomon.chiu@xxxxxxx>
Signed-off-by: Ilya <Ilya.Bakoulin@xxxxxxx>
---
drivers/gpu/drm/amd/display/dc/core/dc_link.c | 16 ++++++++++++++++
.../gpu/drm/amd/display/dc/core/dc_link_ddc.c | 3 +++
2 files changed, 19 insertions(+)
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 48858e31b092..c553d0ea63d3 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link.c
@@ -1197,6 +1197,22 @@ static bool detect_link_and_local_sink(struct dc_link *link,
return false;
}
+
+ if (link->type == dc_connection_sst_branch &&
+ link->dpcd_caps.dongle_type ==
+ DISPLAY_DONGLE_DP_VGA_CONVERTER &&
+ reason == DETECT_REASON_HPDRX) {
+ /* Abort detection for DP-VGA adapters when EDID
+ * can't be read and detection reason is VGA-side
+ * hotplug
+ */
+ if (prev_sink)
+ dc_sink_release(prev_sink);
+ link_disconnect_sink(link);
+
+ return true;
+ }
+
break;
default:
break;
diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c b/drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c
index 24dc662ec3e4..f1bbd918de35 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c
@@ -298,6 +298,9 @@ static uint32_t defer_delay_converter_wa(
if (link->dpcd_caps.dongle_type == DISPLAY_DONGLE_DP_VGA_CONVERTER &&
link->dpcd_caps.branch_dev_id == DP_BRANCH_DEVICE_ID_0080E1 &&
+ (link->dpcd_caps.branch_fw_revision[0] < 0x01 ||
+ (link->dpcd_caps.branch_fw_revision[0] == 0x01 &&
+ link->dpcd_caps.branch_fw_revision[1] < 0x40)) &&
!memcmp(link->dpcd_caps.branch_dev_name,
DP_VGA_DONGLE_BRANCH_DEV_NAME,
sizeof(link->dpcd_caps.branch_dev_name)))
--
2.25.1
