Noticed this while testing 4 ports MST hub from StarTech.com. While plugging in and display a MST monitor(Dell U2417H), change the MST feature to off from OSD. Monitor then can't display anymore.
After analyzing, found out that the CSN reports the specific port from Device with MST Branching Unit (Message_Capability_Status=1 && Peer_Device_Type=010) to SST-only Branch Device ((Message_Capability_Status=0 && Peer_Device_Type=010). Current code expects peer device as MST branch device and can handle sideband message once the peer device type is declared as Peer_Device_Type=010. But for SST-only Branch Device, its Peer_Device_Type is 010 and can't handle sideband message. For this case, we should follow the same handling procedure as the case in DP_PEER_DEVICE_DP_LEGACY_CONV & DP_PEER_DEVICE_SST_SINK. This patch is trying to add the SST-only branch device case in and remain the original processing logic in current code. Changes since v1:(https://patchwork.kernel.org/cover/11323075/) * Squash previous two patches into one patch * Combine if statements to have code cleaner Wayne Lin (1): drm/dp_mst: Handle SST-only branch device case drivers/gpu/drm/drm_dp_mst_topology.c | 140 +++++++++++++++----------- 1 file changed, 80 insertions(+), 60 deletions(-) -- 2.17.1 _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
