f0038cffa8
Expose DRM connector id in device sysfs so that we can map the connector
id to the connector syspath. Currently, even if we can derive the
connector id from modeset, we do not have a way to find the
corresponding connector's syspath.
This is helpful when determining the root connector of MST tree. When a
tree of multiple MST hub is connected to the system, modeset describes
the tree in the PATH blob. For example, consider the following scenario.
+-------------+
| Source | +-------------+
| (Device) | | BranchX |
| | | (MST) |
| [conn6]--->| [port1]--->DisplayA
+-------------+ | |
| | +-------------+
| | | BranchY |
| | | (MST) |
| [port2]--->| [port1]----->DisplayB
+-------------+ | |
| [port2]----->DisplayC
+-------------+
DPMST connector of DisplayA would have "mst:6-1" PATH.
DPMST connector of DisplayB would have "mst:6-2-1" PATH.
DPMST connector of DisplayC would have "mst:6-2-2" PATH.
Given that connector id of 6 is the root of the MST connector tree, we
can utilize this patch to parse through DRM connectors sysfs and find
which connector syspath corresponds to the root connector (id == 6).
ChromeOS intend to use this information for metrics collection. For
example, we want to tell which port is deriving which displays even with
a MST hub. Chromium patch for parsing DRM connector id from the kernel
is at http://crrev.com/c/4317207.
Signed-off-by: Won Chung <wonchung@google.com>
Reviewed-by: Manasi Navare <navaremanasi@chromium.org>
Signed-off-by: Manasi Navare <navaremanasi@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230329014455.1990104-1-wonchung@google.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.