This unifies the driver interface handling between graphics drivers and
makes it easier to change all graphics drivers in lockstep when adding
new features.
Previously inputd would directly push vt activation events to the
graphics driver, which required being quite lazy to prevent deadlocks as
well as the graphics driver having a location where events can be pushed
to. By having graphics drivers pull the vt activation events instead,
the effective control flow becomes simpler and it becomes easier to
correctly handle multiple graphics drivers on the system. For example it
becomes possible for multiple graphics drivers to present displays for a
single VT as well as making it easier to provide a handoff from the
early framebuffer to a real graphics driver.
bjorn3