linux-imx

drm/amd/display: Split enabling CRTC interrupts into two passes

[Why]
When disabling all the pipes for a CRTC the page-flip interrupt also
gets disabled on Raven. We can't re-enable the page-flip interrupt
unless we give DC at least one active DC plane.

We currently enable interrupts after the call to dc_commit_state since
there's currently no valid sequence that should disable all the planes
or re-enable planes for a CRTC without first going through
dc_commit_state.

If we were to allow for a CRTC to be enabled with no primary plane this
would not be the case - the call to dc_commit_updates_for_stream would
enable the planes when going from zero to at least one active plane,
but manage_dm_interrupts would have been called too early.

This results in a page-flip timeout on any subsequent commits since we
think the page-flip are now enabled when they're actually disabled.

We need to enable interrupts after the call to
dc_commit_updates_for_stream.

[How]
Split enabling interrupts into two passes. One pass before
dc_commit_updates_for_stream and one after it.

Shifting all the interrupts to be strictly below the call doesn't
currently work even though it should in theory. We end up queuing
off the vblank event to be handle by the flip handler before it's
actually enabled in some cases, particularly:

old_crtc_state->active = false -> new_crtc_state->active = true

The framebuffer states haven't changed and we can technically still
do a "pageflip" in this case and send back the event.

Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: David Francis <David.Francis@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>