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drm/amd/display: Retry when read dpcd caps failed. 

Some DP panel not detected intermittently due to read dpcd
caps failed when doing hot plug.
[root cause] DC_HPD_CONNECT_INT_DELAY is set to 0, not delay
after HPD toggle and read dpcd data, while some panel need 4ms defer
to read.
[solution] Add a retry when read failed.

Signed-off-by: Yongqiang Sun <yongqiang.sun@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Yongqiang Sun 2018-03-07 09:12:53 -05:00 committed by Alex Deucher
parent ba0a5aaa86
commit 3c1a312aa4
1 changed files with 11 additions and 5 deletions
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16
drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
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@ -2278,6 +2278,8 @@ static bool retrieve_link_cap(struct dc_link *link)
union edp_configuration_cap edp_config_cap;
union dp_downstream_port_present ds_port = { 0 };
enum dc_status status = DC_ERROR_UNEXPECTED;
uint32_t read_dpcd_retry_cnt = 3;
int i;
memset(dpcd_data, '\0', sizeof(dpcd_data));
memset(&down_strm_port_count,
@ -2285,11 +2287,15 @@ static bool retrieve_link_cap(struct dc_link *link)
memset(&edp_config_cap, '\0',
sizeof(union edp_configuration_cap));
status = core_link_read_dpcd(
link,
DP_DPCD_REV,
dpcd_data,
sizeof(dpcd_data));
for (i = 0; i < read_dpcd_retry_cnt; i++) {
status = core_link_read_dpcd(
link,
DP_DPCD_REV,
dpcd_data,
sizeof(dpcd_data));
if (status == DC_OK)
break;
}
if (status != DC_OK) {
dm_error("%s: Read dpcd data failed.\n", __func__);