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drm/amd/display: Passive DP->HDMI dongle detection fix 

[WHY]
i2c_read is called to differentiate passive DP->HDMI and DP->DVI-D dongles
The call is expected to fail in DVI-D case but pass in HDMI case
Some HDMI dongles have a chance to fail as well, causing misdetection as DVI-D

[HOW]
Retry i2c_read to ensure failed result is valid

Signed-off-by: Michael Strauss <michael.strauss@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:
Michael Strauss 2019-10-03 11:54:15 -04:00 committed by Alex Deucher
parent 7c37d399c2
commit bc2fde42e2
1 changed files with 18 additions and 6 deletions
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12
drivers/gpu/drm/amd/display/dc/core/dc_link_ddc.c
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@ -374,6 +374,7 @@ void dal_ddc_service_i2c_query_dp_dual_mode_adaptor(
enum display_dongle_type *dongle = &sink_cap->dongle_type;
uint8_t type2_dongle_buf[DP_ADAPTOR_TYPE2_SIZE];
bool is_type2_dongle = false;
int retry_count = 2;
struct dp_hdmi_dongle_signature_data *dongle_signature;
/* Assume we have no valid DP passive dongle connected */
@ -386,6 +387,16 @@ void dal_ddc_service_i2c_query_dp_dual_mode_adaptor(
DP_HDMI_DONGLE_ADDRESS,
type2_dongle_buf,
sizeof(type2_dongle_buf))) {
/* Passive HDMI dongles can sometimes fail here without retrying*/
while (retry_count > 0) {
if (i2c_read(ddc,
DP_HDMI_DONGLE_ADDRESS,
type2_dongle_buf,
sizeof(type2_dongle_buf)))
break;
retry_count--;
}
if (retry_count == 0) {
*dongle = DISPLAY_DONGLE_DP_DVI_DONGLE;
sink_cap->max_hdmi_pixel_clock = DP_ADAPTOR_DVI_MAX_TMDS_CLK;
@ -394,6 +405,7 @@ void dal_ddc_service_i2c_query_dp_dual_mode_adaptor(
DP_ADAPTOR_DVI_MAX_TMDS_CLK / 1000);
return;
}
}
/* Check if Type 2 dongle.*/
if (type2_dongle_buf[DP_ADAPTOR_TYPE2_REG_ID] == DP_ADAPTOR_TYPE2_ID)