Commit 0fb915d6 authored by Mario Limonciello's avatar Mario Limonciello Committed by Alex Deucher
Browse files

drm/amd/display: Only enable common modes for eDP and LVDS 



[Why]
The main reason common modes are added is for compatibility with
clone mode when a laptop is connected to a projector or external
monitor.  Since commit 978fa2f6 ("drm/amd/display: Use scaling
for non-native resolutions on eDP") when non-native modes are picked
for eDP the GPU scalar will be used.  This is because it is inconsistent
whether eDP panels have the capability to actually drive non-native
resolutions. With panels connected to other connectors this limitation
generally doesn't exist as we the EDID will advertise support for a
number of resolutions and monitors will use built in scaling hardware.

Comparing DC and non-DC code paths the non-DC code path only adds
common modes for LVDS and eDP whereas the DC codepath does it for
all connector types.

In the past there was an experiment done to disable common mode adding
for eDP and LVDS from commit 6d396e7a ("drm/amd/display: Disable
common modes for LVDS") and commit 7948afb4 ("drm/amd/display:
Disable common modes for eDP") but this was reverted in
commit a8b79b09 ("drm/amd: Re-enable common modes for eDP and
LVDS") because it caused problems with Xorg.

[How]
Only add common modes for eDP and LVDS for DC, matching the behavior
of non-DC.

Suggested-by: default avatarTimur Kristóf <timur.kristof@gmail.com>
Reviewed-by: default avatarHarry Wentland <harry.wentland@amd.com>
Reviewed-by: default avatarTimur Kristóf <timur.kristof@gmail.com>
Reviewed-by: default avatarAlex Deucher <alexander.deucher@amd.com>
Link: https://lore.kernel.org/r/20250924161624.1975819-2-mario.limonciello@amd.com


Signed-off-by: default avatarMario Limonciello <mario.limonciello@amd.com>
Signed-off-by: default avatarAlex Deucher <alexander.deucher@amd.com>
parent 4e3b45d7

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

+4 −0
Original line number Diff line number Diff line
@@ -8271,6 +8271,10 @@ static void amdgpu_dm_connector_add_common_modes(struct drm_encoder *encoder, 
		{"1920x1200", 1920, 1200}

	};



	if ((connector->connector_type != DRM_MODE_CONNECTOR_eDP) &&

	    (connector->connector_type != DRM_MODE_CONNECTOR_LVDS))

		return;



	n = ARRAY_SIZE(common_modes);



	for (i = 0; i < n; i++) {