Commit a1362c40 authored Oct 08, 2025 by Meenakshikumar Somasundaram Committed by Alex Deucher Oct 20, 2025

drm/amd/display: write segment pointer with mot enabled for mst



[Why]
Some mst branches NAK's segment pointer writes with mot disabled.
So reset of segment pointer to 0 should be performed with mot enabled.

[How]
Write segment pointer of mst branch devices with mot enabled.

Reviewed-by: Cruise Hung <cruise.hung@amd.com>
Signed-off-by: Meenakshikumar Somasundaram <meenakshikumar.somasundaram@amd.com>
Signed-off-by: Tom Chung <chiahsuan.chung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

parent 1319fb80

drivers/gpu/drm/amd/display/dc/link/link_factory.c

+0 −3

Original line number	Diff line number	Diff line
		@@ -817,9 +817,6 @@ static bool construct_dpia(struct dc_link *link,

		link->psr_settings.psr_version = DC_PSR_VERSION_UNSUPPORTED;

		/* Some docks seem to NAK I2C writes to segment pointer with mot=0. */
		link->wa_flags.dp_mot_reset_segment = true;

		return true;

		ddc_create_fail:

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

+6 −0

Original line number	Diff line number	Diff line
		@@ -1867,6 +1867,12 @@ static bool retrieve_link_cap(struct dc_link *link)
		link->dpcd_caps.is_mst_capable = read_is_mst_supported(link);
		DC_LOG_DC("%s: MST_Support: %s\n", __func__, str_yes_no(link->dpcd_caps.is_mst_capable));

		/* Some MST docks seem to NAK I2C writes to segment pointer with mot=0. */
		if (link->dpcd_caps.is_mst_capable)
		link->wa_flags.dp_mot_reset_segment = true;
		else
		link->wa_flags.dp_mot_reset_segment = false;

		get_active_converter_info(ds_port.byte, link);

		dp_wa_power_up_0010FA(link, dpcd_data, sizeof(dpcd_data));