drm/dp_mst: Add new quirk for Synaptics MST hubs
authorMikita Lipski <mikita.lipski@amd.com>
Fri, 20 Sep 2019 19:44:56 +0000 (15:44 -0400)
committerAlex Deucher <alexander.deucher@amd.com>
Thu, 9 Jan 2020 23:07:46 +0000 (18:07 -0500)
commit5b03f9d86880711441c5681244d352212460a595
tree5d68dab858a86e32557aa33de34b8cb6ed1becdd
parentc2bc1b6eabe65d6bf26a892d803907dca9097311
drm/dp_mst: Add new quirk for Synaptics MST hubs

Synaptics DP1.4 hubs (BRANCH_ID 0x90CC24) do not
support virtual DPCD registers, but do support DSC.
The DSC caps can be read from the physical aux,
like in SST DSC. These hubs have many different
DEVICE_IDs.  Add a new quirk to detect this case.

v2: Fix error when checking return of drm_dp_read_desc

Reviewed-by: Wenjing Liu <Wenjing.Liu@amd.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Signed-off-by: David Francis <David.Francis@amd.com>
Signed-off-by: Mikita Lipski <mikita.lipski@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
drivers/gpu/drm/drm_dp_helper.c
drivers/gpu/drm/drm_dp_mst_topology.c
include/drm/drm_dp_helper.h