This adds "restore-crtc" property using which one
can restore previous crtc mode.
By default it is enabled, if CRTC was already
active with a valid mode and kmssink set a new mode
on CRTC using force-modesetting.
This helps user restore previous crtc mode and get
the previous session back after running a kmssink
pipeline involving a force-modesetting.
For e.g. When running a kmssink pipeline on rpi
using force-modesetting on tty console, it was giving
a blank screen after pipeline, and now with help of restore-crtc
functionality, CRTC is set with previous crtc mode
previously active on tty console.
Edited-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
https://bugzilla.gnome.org/show_bug.cgi?id=797025
7d79378895