Commit 791897f5 authored by Michael Strauss's avatar Michael Strauss Committed by Alex Deucher
Browse files

drm/amd/display: Get LTTPR IEEE OUI/Device ID From Closest LTTPR To Host 



[WHY]
These fields are read for the explicit purpose of detecting embedded LTTPRs
(i.e. between host ASIC and the user-facing port), and thus need to
calculate the correct DPCD address offset based on LTTPR count to target
the appropriate LTTPR's DPCD register space with these queries.

[HOW]
Cascaded LTTPRs in a link each snoop and increment LTTPR count when queried
via DPCD read, so an LTTPR embedded in a source device (e.g. USB4 port on a
laptop) will always be addressible using the max LTTPR count seen by the
host. Therefore we simply need to use a recently added helper function to
calculate the correct DPCD address to target potentially embedded LTTPRs
based on the received LTTPR count.

Cc: Mario Limonciello <mario.limonciello@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: default avatarWenjing Liu <wenjing.liu@amd.com>
Signed-off-by: default avatarMichael Strauss <michael.strauss@amd.com>
Signed-off-by: default avatarAlex Hung <alex.hung@amd.com>
Tested-by: default avatarDaniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent c6618fa8

drivers/gpu/drm/amd/display/dc/dc_dp_types.h

+2 −2
Original line number Diff line number Diff line
@@ -1172,8 +1172,8 @@ struct dc_lttpr_caps { 
	union dp_128b_132b_supported_lttpr_link_rates supported_128b_132b_rates;

	union dp_alpm_lttpr_cap alpm;

	uint8_t aux_rd_interval[MAX_REPEATER_CNT - 1];

	uint8_t lttpr_ieee_oui[3];

	uint8_t lttpr_device_id[6];

	uint8_t lttpr_ieee_oui[3]; // Always read from closest LTTPR to host

	uint8_t lttpr_device_id[6]; // Always read from closest LTTPR to host

};



struct dc_dongle_dfp_cap_ext {

drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_capability.c

+31 −7
Original line number Diff line number Diff line
@@ -385,9 +385,15 @@ bool dp_is_128b_132b_signal(struct pipe_ctx *pipe_ctx) 
bool dp_is_lttpr_present(struct dc_link *link)

{

	/* Some sink devices report invalid LTTPR revision, so don't validate against that cap */

	return (dp_parse_lttpr_repeater_count(link->dpcd_caps.lttpr_caps.phy_repeater_cnt) != 0 &&

	uint32_t lttpr_count = dp_parse_lttpr_repeater_count(link->dpcd_caps.lttpr_caps.phy_repeater_cnt);

	bool is_lttpr_present = (lttpr_count > 0 &&

			link->dpcd_caps.lttpr_caps.max_lane_count > 0 &&

			link->dpcd_caps.lttpr_caps.max_lane_count <= 4);



	if (lttpr_count > 0 && !is_lttpr_present)

		DC_LOG_ERROR("LTTPR count is nonzero but invalid lane count reported. Assuming no LTTPR present.\n");



	return is_lttpr_present;

}



/* in DP compliance test, DPR-120 may have
@@ -1551,6 +1557,8 @@ enum dc_status dp_retrieve_lttpr_cap(struct dc_link *link) 
	uint8_t lttpr_dpcd_data[10] = {0};

	enum dc_status status;

	bool is_lttpr_present;

	uint32_t lttpr_count;

	uint32_t closest_lttpr_offset;



	/* Logic to determine LTTPR support*/

	bool vbios_lttpr_interop = link->dc->caps.vbios_lttpr_aware;
@@ -1602,20 +1610,22 @@ enum dc_status dp_retrieve_lttpr_cap(struct dc_link *link) 
			lttpr_dpcd_data[DP_LTTPR_ALPM_CAPABILITIES -

							DP_LT_TUNABLE_PHY_REPEATER_FIELD_DATA_STRUCTURE_REV];



	lttpr_count = dp_parse_lttpr_repeater_count(link->dpcd_caps.lttpr_caps.phy_repeater_cnt);



	/* If this chip cap is set, at least one retimer must exist in the chain

	 * Override count to 1 if we receive a known bad count (0 or an invalid value) */

	if (((link->chip_caps & AMD_EXT_DISPLAY_PATH_CAPS__EXT_CHIP_MASK) == AMD_EXT_DISPLAY_PATH_CAPS__DP_FIXED_VS_EN) &&

			(dp_parse_lttpr_repeater_count(link->dpcd_caps.lttpr_caps.phy_repeater_cnt) == 0)) {

			lttpr_count == 0) {

		/* If you see this message consistently, either the host platform has FIXED_VS flag

		 * incorrectly configured or the sink device is returning an invalid count.

		 */

		DC_LOG_ERROR("lttpr_caps phy_repeater_cnt is 0x%x, forcing it to 0x80.",

			     link->dpcd_caps.lttpr_caps.phy_repeater_cnt);

		link->dpcd_caps.lttpr_caps.phy_repeater_cnt = 0x80;

		lttpr_count = 1;

		DC_LOG_DC("lttpr_caps forced phy_repeater_cnt = %d\n", link->dpcd_caps.lttpr_caps.phy_repeater_cnt);

	}



	/* Attempt to train in LTTPR transparent mode if repeater count exceeds 8. */

	is_lttpr_present = dp_is_lttpr_present(link);



	DC_LOG_DC("is_lttpr_present = %d\n", is_lttpr_present);
@@ -1623,11 +1633,25 @@ enum dc_status dp_retrieve_lttpr_cap(struct dc_link *link) 
	if (is_lttpr_present) {

		CONN_DATA_DETECT(link, lttpr_dpcd_data, sizeof(lttpr_dpcd_data), "LTTPR Caps: ");



		core_link_read_dpcd(link, DP_LTTPR_IEEE_OUI, link->dpcd_caps.lttpr_caps.lttpr_ieee_oui, sizeof(link->dpcd_caps.lttpr_caps.lttpr_ieee_oui));

		CONN_DATA_DETECT(link, link->dpcd_caps.lttpr_caps.lttpr_ieee_oui, sizeof(link->dpcd_caps.lttpr_caps.lttpr_ieee_oui), "LTTPR IEEE OUI: ");

		// Identify closest LTTPR to determine if workarounds required for known embedded LTTPR

		closest_lttpr_offset = dp_get_closest_lttpr_offset(lttpr_count);



		core_link_read_dpcd(link, DP_LTTPR_DEVICE_ID, link->dpcd_caps.lttpr_caps.lttpr_device_id, sizeof(link->dpcd_caps.lttpr_caps.lttpr_device_id));

		CONN_DATA_DETECT(link, link->dpcd_caps.lttpr_caps.lttpr_device_id, sizeof(link->dpcd_caps.lttpr_caps.lttpr_device_id), "LTTPR Device ID: ");

		core_link_read_dpcd(link, (DP_LTTPR_IEEE_OUI + closest_lttpr_offset),

				link->dpcd_caps.lttpr_caps.lttpr_ieee_oui, sizeof(link->dpcd_caps.lttpr_caps.lttpr_ieee_oui));

		core_link_read_dpcd(link, (DP_LTTPR_DEVICE_ID + closest_lttpr_offset),

				link->dpcd_caps.lttpr_caps.lttpr_device_id, sizeof(link->dpcd_caps.lttpr_caps.lttpr_device_id));



		if (lttpr_count > 1) {

			CONN_DATA_DETECT(link, link->dpcd_caps.lttpr_caps.lttpr_ieee_oui, sizeof(link->dpcd_caps.lttpr_caps.lttpr_ieee_oui),

					"Closest LTTPR To Host's IEEE OUI: ");

			CONN_DATA_DETECT(link, link->dpcd_caps.lttpr_caps.lttpr_device_id, sizeof(link->dpcd_caps.lttpr_caps.lttpr_device_id),

					"Closest LTTPR To Host's LTTPR Device ID: ");

		} else {

			CONN_DATA_DETECT(link, link->dpcd_caps.lttpr_caps.lttpr_ieee_oui, sizeof(link->dpcd_caps.lttpr_caps.lttpr_ieee_oui),

					"LTTPR IEEE OUI: ");

			CONN_DATA_DETECT(link, link->dpcd_caps.lttpr_caps.lttpr_device_id, sizeof(link->dpcd_caps.lttpr_caps.lttpr_device_id),

					"LTTPR Device ID: ");

		}

	}



	return status;