Commit 77361ed8 authored by Jimmy Kizito's avatar Jimmy Kizito Committed by Alex Deucher
Browse files

drm/amd/display: Avoid reading LTTPR caps in non-LTTPR mode. 



[Why]
LTTPR capable devices on the DisplayPort path may assume that
extended LTTPR AUX timeouts will be used after LTTPR capabilities
are read.

When DPTX operates in non-LTTPR mode, AUX timeouts are not
extended and this can result in AUX transactions timing out.

[How]
Use shared helper function to determine LTTPR mode and do not
read LTTPR capabilities in non-LTTPR mode.

Reviewed-by: default avatarMustapha Ghaddar <Mustapha.Ghaddar@amd.com>
Reviewed-by: default avatarMeenakshikumar Somasundaram <Meenakshikumar.Somasundaram@amd.com>
Reviewed-by: default avatarJun Lei <Jun.Lei@amd.com>
Acked-by: default avatarHamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: default avatarJimmy Kizito <Jimmy.Kizito@amd.com>
Tested-by: default avatarDaniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent 165ab7b4

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

+31 −13
Original line number Diff line number Diff line
@@ -5129,16 +5129,13 @@ static bool dpcd_read_sink_ext_caps(struct dc_link *link) 
	return true;

}



bool dp_retrieve_lttpr_cap(struct dc_link *link)

/* Logic to determine LTTPR mode */

static void determine_lttpr_mode(struct dc_link *link)

{

	uint8_t lttpr_dpcd_data[8];

	bool allow_lttpr_non_transparent_mode = 0;

	bool vbios_lttpr_enable = link->dc->caps.vbios_lttpr_enable;

	bool vbios_lttpr_interop = link->dc->caps.vbios_lttpr_aware;

	enum dc_status status = DC_ERROR_UNEXPECTED;

	bool is_lttpr_present = false;



	memset(lttpr_dpcd_data, '\0', sizeof(lttpr_dpcd_data));



	if ((link->dc->config.allow_lttpr_non_transparent_mode.bits.DP2_0 &&

			link->dpcd_caps.channel_coding_cap.bits.DP_128b_132b_SUPPORTED)) {
@@ -5148,9 +5145,6 @@ bool dp_retrieve_lttpr_cap(struct dc_link *link) 
		allow_lttpr_non_transparent_mode = 1;

	}



	/*

	 * Logic to determine LTTPR mode

	 */

	link->lttpr_mode = LTTPR_MODE_NON_LTTPR;

	if (vbios_lttpr_enable && vbios_lttpr_interop)

		link->lttpr_mode = LTTPR_MODE_NON_TRANSPARENT;
@@ -5172,6 +5166,18 @@ bool dp_retrieve_lttpr_cap(struct dc_link *link) 
	    link->dc->debug.dpia_debug.bits.force_non_lttpr)

		link->lttpr_mode = LTTPR_MODE_NON_LTTPR;

#endif

}



bool dp_retrieve_lttpr_cap(struct dc_link *link)

{

	uint8_t lttpr_dpcd_data[8];

	enum dc_status status = DC_ERROR_UNEXPECTED;

	bool is_lttpr_present = false;



	memset(lttpr_dpcd_data, '\0', sizeof(lttpr_dpcd_data));



	/* Logic to determine LTTPR mode*/

	determine_lttpr_mode(link);



	if (link->lttpr_mode == LTTPR_MODE_NON_TRANSPARENT || link->lttpr_mode == LTTPR_MODE_TRANSPARENT) {

		/* By reading LTTPR capability, RX assumes that we will enable
@@ -5287,11 +5293,23 @@ static enum dc_status wa_try_to_wake_dprx(struct dc_link *link, uint64_t timeout 
	uint64_t time_taken_ms = 0;

	enum dc_connection_type type = dc_connection_none;



	determine_lttpr_mode(link);



	/* Issue an AUX read to test DPRX responsiveness. If LTTPR is supported the first read is expected to

	 * be to determine LTTPR capabilities. Otherwise trying to read power state should be an innocuous AUX read.

	 */

	if (link->lttpr_mode == LTTPR_MODE_NON_TRANSPARENT || link->lttpr_mode == LTTPR_MODE_TRANSPARENT)

		status = core_link_read_dpcd(

				link,

				DP_LT_TUNABLE_PHY_REPEATER_FIELD_DATA_STRUCTURE_REV,

				&dpcd_data,

				sizeof(dpcd_data));

	else

		status = core_link_read_dpcd(

				link,

				DP_SET_POWER,

				&dpcd_data,

				sizeof(dpcd_data));



	if (status != DC_OK) {

		DC_LOG_WARNING("%s: Read DPCD LTTPR_CAP failed - try to toggle DPCD SET_POWER for %lld ms.",