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[Why] Need to be able to trigger software hotplug for MST connectors [How] For unplug the driver calls to disable topologies manager that connector is attached to. For plugging in it does the whole rediscovery of all connectors in drm device and enbles their topologies if attached. The interface for MST connectors works in the following way: 1. To disconnect all MST topologies currently connected: echo 0 > /sys/kernel/debug/dri/0/amdgpu_dm_trigger_hpd_mst 2. To reconnect/rediscover all topologies that are physically connected to the card: echo 1 > /sys/kernel/debug/dri/0/amdgpu_dm_trigger_hpd_mst A related fix which has been merged with this patch Leo Ma(Hanghong Ma)'s work: Set power states before disable MST topology [Why] When we try to disable MST topology from the debugfs entry, some receiver will hang. [How] Set DPCD 600h power states to 2(power down mode)before disable MST topology. Signed-off-by: Mikita Lipski <mikita.lipski@amd.com> Reviewed-by: Sun peng Li <Sunpeng.Li@amd.com> Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com> Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.