drm/tegra: dc: Select root window for event dispatch
drm/tegra: dc: Select root window for event dispatch

In finish pageflip, the driver was not selecting the root window when
dispatching events. This exposed a race where a plane update would
change the window selection and cause tegra_dc_finish_page_flip to check
the wrong base address.

This patch also protects access to the window selection register as well
as the registers affected by it.

Signed-off-by: Sean Paul <f9352ecf3e2294bdb914c99cca8d12601acec118@chromium.org>
Signed-off-by: Thierry Reding <3055038c414aef68bf32c33b8118623e7554e0f2@nvidia.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs