Commit bc2fde42 authored by Michael Strauss's avatar Michael Strauss Committed by Alex Deucher
Browse files

drm/amd/display: Passive DP->HDMI dongle detection fix 



[WHY]
i2c_read is called to differentiate passive DP->HDMI and DP->DVI-D dongles
The call is expected to fail in DVI-D case but pass in HDMI case
Some HDMI dongles have a chance to fail as well, causing misdetection as DVI-D

[HOW]
Retry i2c_read to ensure failed result is valid

Signed-off-by: default avatarMichael Strauss <michael.strauss@amd.com>
Reviewed-by: default avatarTony Cheng <Tony.Cheng@amd.com>
Acked-by: default avatarLeo Li <sunpeng.li@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent 7c37d399

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

+18 −6
Original line number Diff line number Diff line
@@ -374,6 +374,7 @@ void dal_ddc_service_i2c_query_dp_dual_mode_adaptor( 
	enum display_dongle_type *dongle = &sink_cap->dongle_type;

	uint8_t type2_dongle_buf[DP_ADAPTOR_TYPE2_SIZE];

	bool is_type2_dongle = false;

	int retry_count = 2;

	struct dp_hdmi_dongle_signature_data *dongle_signature;



	/* Assume we have no valid DP passive dongle connected */
@@ -386,6 +387,16 @@ void dal_ddc_service_i2c_query_dp_dual_mode_adaptor( 
		DP_HDMI_DONGLE_ADDRESS,

		type2_dongle_buf,

		sizeof(type2_dongle_buf))) {

		/* Passive HDMI dongles can sometimes fail here without retrying*/

		while (retry_count > 0) {

			if (i2c_read(ddc,

				DP_HDMI_DONGLE_ADDRESS,

				type2_dongle_buf,

				sizeof(type2_dongle_buf)))

				break;

			retry_count--;

		}

		if (retry_count == 0) {

			*dongle = DISPLAY_DONGLE_DP_DVI_DONGLE;

			sink_cap->max_hdmi_pixel_clock = DP_ADAPTOR_DVI_MAX_TMDS_CLK;
@@ -394,6 +405,7 @@ void dal_ddc_service_i2c_query_dp_dual_mode_adaptor( 
					DP_ADAPTOR_DVI_MAX_TMDS_CLK / 1000);

			return;

		}

	}



	/* Check if Type 2 dongle.*/

	if (type2_dongle_buf[DP_ADAPTOR_TYPE2_REG_ID] == DP_ADAPTOR_TYPE2_ID)