drm/i915: Use the correct crtc when sanitizing plane mapping

drm/i915: Use the correct crtc when sanitizing plane mapping

When we decide that a plane is attached to the wrong pipe we try
to turn off said plane. However we are passing around the crtc we
think that the plane is supposed to be using rather than the crtc
it is currently using. That doesn't work all that well because
we may have to do vblank waits etc. and the other pipe might
not even be enabled here. So let's pass the plane's current crtc to
intel_plane_disable_noatomic() so that it can its job correctly.

To do that semi-cleanly we also have to change the plane readout
to record the plane's visibility into the bitmasks of the crtc
where the plane is currently enabled rather than to the crtc
we want to use for the plane.

One caveat here is that our active_planes bitmask will get confused
if both planes are enabled on the same pipe. Fortunately we can use
plane_mask to reconstruct active_planes sufficiently since
plane_mask still has the same meaning (is the plane visible?)
during readout. We also have to do the same during the initial
plane readout as the second plane could clear the active_planes
bit the first plane had already set.

v2: Rely on fixup_active_planes() to populate active_planes fully (Daniel)
    Add Daniel's proposed comment to better document why we do this
    Drop the redundant intel_set_plane_visible() call

Cc: stable@vger.kernel.org # fcba862e8428 drm/i915: Have plane->get_hw_state() return the current pipe
Cc: stable@vger.kernel.org
Cc: Dennis <dennis.nezic@utoronto.ca>
Cc: Daniel Vetter <daniel@ffwll.ch>
Tested-by: Dennis <dennis.nezic@utoronto.ca>
Tested-by: Peter Nowee <peter.nowee@gmail.com>
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=105637
Fixes: b1e01595a66d ("drm/i915: Redo plane sanitation during readout")
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20181003145017.4527-1-ville.syrjala@linux.intel.com
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>