Commit 6ebdaf20 authored by Lewis Huang's avatar Lewis Huang Committed by Alex Deucher
Browse files

drm/amd/display: Refine aux transaction before retrieve caps 



[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: default avatarJimmy Kizito <Jimmy.Kizito@amd.com>
Acked-by: default avatarBrian Chang <Brian.Chang@amd.com>
Signed-off-by: default avatarLewis Huang <Lewis.Huang@amd.com>
Tested-by: default avatarDaniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent 9af611f2

drivers/gpu/drm/amd/display/dc/core/dc_link_dp.c

+34 −11
Original line number Diff line number Diff line
@@ -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
@@ -5302,10 +5303,7 @@ static bool retrieve_link_cap(struct dc_link *link) 
		status = wa_try_to_wake_dprx(link, timeout_ms);

	}



	is_lttpr_present = dp_retrieve_lttpr_cap(link);

	/* Read DP tunneling information. */

	status = dpcd_get_tunneling_device_data(link);



	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));
@@ -5314,8 +5312,33 @@ static bool retrieve_link_cap(struct dc_link *link) 
		 * 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)

		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);



	dpcd_set_source_specific_data(link);

	/* Sink may need to configure internals based on vendor, so allow some