From: Dale Zhao <dale.z...@amd.com>
[Why]:
According to eDP spec, max T7 delay should be 50 ms. Current code uses 300
retry counters may not be accurate enough for different panels.
[How]:
Use absolute time stamp to achive accurate delay.
Signed-off-by: Dale Zhao <dale.z...@amd.com>
Reviewed-by: Anthony Koo <anthony....@amd.com>
Acked-by: Rodrigo Siqueira <rodrigo.sique...@amd.com>
---
drivers/gpu/drm/amd/display/dc/core/dc_link_hwss.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_link_hwss.c
b/drivers/gpu/drm/amd/display/dc/core/dc_link_hwss.c
index 548aac02ca11..d1df0541e10a 100644
--- a/drivers/gpu/drm/amd/display/dc/core/dc_link_hwss.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_link_hwss.c
@@ -173,15 +173,20 @@ bool edp_receiver_ready_T9(struct dc_link *link)
}
bool edp_receiver_ready_T7(struct dc_link *link)
{
- unsigned int tries = 0;
unsigned char sinkstatus = 0;
unsigned char edpRev = 0;
enum dc_status result = DC_OK;
+ /* use absolute time stamp to constrain max T7*/
+ unsigned long long enter_timestamp = 0;
+ unsigned long long finish_timestamp = 0;
+ unsigned long long time_taken_in_ns = 0;
+
result = core_link_read_dpcd(link, DP_EDP_DPCD_REV, &edpRev,
sizeof(edpRev));
if (result == DC_OK && edpRev < DP_EDP_12)
return true;
/* start from eDP version 1.2, SINK_STAUS indicate the sink is ready.*/
+ enter_timestamp = dm_get_timestamp(link->ctx);
do {
sinkstatus = 0;
result = core_link_read_dpcd(link, DP_SINK_STATUS, &sinkstatus,
sizeof(sinkstatus));
@@ -189,8 +194,10 @@ bool edp_receiver_ready_T7(struct dc_link *link)
break;
if (result != DC_OK)
break;
- udelay(25); //MAx T7 is 50ms
- } while (++tries < 300);
+ udelay(25);
+ finish_timestamp = dm_get_timestamp(link->ctx);
+ time_taken_in_ns = dm_get_elapse_time_in_ns(link->ctx,
finish_timestamp, enter_timestamp);
+ } while (time_taken_in_ns < 50 * 1000000); //MAx T7 is 50ms
if (link->local_sink->edid_caps.panel_patch.extra_t7_ms > 0)
udelay(link->local_sink->edid_caps.panel_patch.extra_t7_ms *
1000);
--
2.24.0
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