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drm/amd/display: add workaround flag to link to force FFE preset

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[Why]
There have been instances of some monitors being unable to link train on
their reported link speed using their selected FFE preset. If a different
FFE preset is found that has a higher rate of success during link training
this workaround can be used to force its FFE preset.

[How]
A new link workaround flag is made called force_dp_ffe_preset. The flag is
checked in override_training_settings and will set lt_settings->ffe_preset
which is null if the flag is not set. The flag is then set in
override_lane_settings.

Reviewed-by: Wenjing Liu <wenjing.liu@amd.com>
Signed-off-by: Brendan Tam <Brendan.Tam@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Brendan Tam 2025-01-23 11:25:16 -05:00 committed by Alex Deucher
parent 5a20ca32a2
commit 51d1b33854
2 changed files with 4 additions and 0 deletions
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2
drivers/gpu/drm/amd/display/dc/dc.h
View File

@ -1792,7 +1792,9 @@ struct dc_link {
bool dongle_mode_timing_override;
bool blank_stream_on_ocs_change;
bool read_dpcd204h_on_irq_hpd;
bool force_dp_ffe_preset;
} wa_flags;
union dc_dp_ffe_preset forced_dp_ffe_preset;
struct link_mst_stream_allocation_table mst_stream_alloc_table;
struct dc_link_status link_status;

2
drivers/gpu/drm/amd/display/dc/link/protocols/link_dp_training.c
View File

@ -736,6 +736,8 @@ void override_training_settings(
lt_settings->pre_emphasis = overrides->pre_emphasis;
if (overrides->post_cursor2 != NULL)
lt_settings->post_cursor2 = overrides->post_cursor2;
if (link->wa_flags.force_dp_ffe_preset && !dp_is_lttpr_present(link))
lt_settings->ffe_preset = &link->forced_dp_ffe_preset;
if (overrides->ffe_preset != NULL)
lt_settings->ffe_preset = overrides->ffe_preset;
/* Override HW lane settings with BIOS forced values if present */