From: Lewis Huang <Lewis.Huang@xxxxxxx>
[Why]
LTTPR caps will read fail if aux channel is not active.
[How]
1.Perform 600 read upto 10 retry with 1ms delay in between.
2.If fail, return false and trigger another retry detection.
3.If pass, read LTTPR caps in retrieve link caps.
Reviewed-by: Jimmy Kizito <Jimmy.Kizito@xxxxxxx>
Acked-by: Brian Chang <Brian.Chang@xxxxxxx>
Signed-off-by: Lewis Huang <Lewis.Huang@xxxxxxx>
---
.../gpu/drm/amd/display/dc/core/dc_link_dp.c | 45 ++++++++++++++-----
1 file changed, 34 insertions(+), 11 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
index 2b7bb3a796e8..8617de559174 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c
@@ -5275,6 +5275,7 @@ static bool retrieve_link_cap(struct dc_link *link)
union dp_downstream_port_present ds_port = { 0 };
enum dc_status status = DC_ERROR_UNEXPECTED;
uint32_t read_dpcd_retry_cnt = 3;
+ uint32_t aux_channel_retry_cnt = 0;
int i;
struct dp_sink_hw_fw_revision dp_hw_fw_revision;
const uint32_t post_oui_delay = 30; // 30ms
@@ -5302,21 +5303,43 @@ static bool retrieve_link_cap(struct dc_link *link)
status = wa_try_to_wake_dprx(link, timeout_ms);
}
+ while (status != DC_OK && aux_channel_retry_cnt < 10) {
+ status = core_link_read_dpcd(link, DP_SET_POWER,
+ &dpcd_power_state, sizeof(dpcd_power_state));
+
+ /* Delay 1 ms if AUX CH is in power down state. Based on spec
+ * section 2.3.1.2, if AUX CH may be powered down due to
+ * write to DPCD 600h = 2. Sink AUX CH is monitoring differential
+ * signal and may need up to 1 ms before being able to reply.
+ */
+ if (status != DC_OK || dpcd_power_state == DP_SET_POWER_D3) {
+ udelay(1000);
+ aux_channel_retry_cnt++;
+ }
+ }
+
+ /* If aux channel is not active, return false and trigger another detect*/
+ if (status != DC_OK) {
+ dpcd_power_state = DP_SET_POWER_D0;
+ status = core_link_write_dpcd(
+ link,
+ DP_SET_POWER,
+ &dpcd_power_state,
+ sizeof(dpcd_power_state));
+
+ dpcd_power_state = DP_SET_POWER_D3;
+ status = core_link_write_dpcd(
+ link,
+ DP_SET_POWER,
+ &dpcd_power_state,
+ sizeof(dpcd_power_state));
+ return false;
+ }
+
is_lttpr_present = dp_retrieve_lttpr_cap(link);
/* Read DP tunneling information. */
status = dpcd_get_tunneling_device_data(link);
- status = core_link_read_dpcd(link, DP_SET_POWER,
- &dpcd_power_state, sizeof(dpcd_power_state));
-
- /* Delay 1 ms if AUX CH is in power down state. Based on spec
- * section 2.3.1.2, if AUX CH may be powered down due to
- * write to DPCD 600h = 2. Sink AUX CH is monitoring differential
- * signal and may need up to 1 ms before being able to reply.
- */
- if (status != DC_OK || dpcd_power_state == DP_SET_POWER_D3)
- udelay(1000);
-
dpcd_set_source_specific_data(link);
/* Sink may need to configure internals based on vendor, so allow some
* time before proceeding with possibly vendor specific transactions
--
2.25.1
