drm/amd/display: Use DAC load detection on analog connectors (v2)

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This feature is useful for analog connections without EDID:
- Really old monitors with a VGA connector
- Cheap DVI/VGA adapters that don't connect DDC pins

When a connection is established through DAC load detection,
the driver is supposed to fill in the supported modes for the
display, which we already do in amdgpu_dm_connector_get_modes.

Also, because the load detection causes visible glitches, do not
attempt to poll the connector again after it was detected this
way. Note that it will still be polled after sleep/resume or
when force is enabled, which is okay.

v2:
Add dc_connection_dac_load connection type.
Properly release sink when no display is connected.
Don't print error when EDID isn't read from an analog display.

Signed-off-by: Timur Kristóf <timur.kristof@gmail.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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This commit is contained in:

Timur Kristóf 2025-09-26 20:02:00 +02:00 • committed by Alex Deucher

parent d75e45b853

commit ac1bb49522

3 changed files with 72 additions and 2 deletions

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10

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

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3

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

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61

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

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