drm: Use of-graph helpers to loop over endpoints

Convert all drm callers that use of_graph_get_next_endpoint to loop over
of-graph endpoints to the newly introduced for_each_endpoint_of_node
helper macro.

* tag 'of-graph-drm-2015-04-08' of git://git.pengutronix.de/git/pza/linux:
  drm/rockchip: use for_each_endpoint_of_node macro, drop endpoint reference on break
  drm/rcar-du: use for_each_endpoint_of_node macro
  drm/imx: use for_each_endpoint_of_node macro in imx_drm_encoder_get_mux_id
  drm: use for_each_endpoint_of_node macro in drm_of_find_possible_crtcs
  of: Explicitly include linux/types.h in of_graph.h
  dt-bindings: brcm: rationalize Broadcom documentation naming
  of/unittest: replace 'selftest' with 'unittest'
  Documentation: rename of_selftest.txt to of_unittest.txt
  Documentation: update the of_selftest.txt
  dt: OF_UNITTEST make dependency broken
  MAINTAINERS: Pantelis Antoniou device tree overlay maintainer
  of: Add of_graph_get_port_by_id function
  of: Add for_each_endpoint_of_node helper macro
  of: Decrement refcount of previous endpoint in of_graph_get_next_endpoint

Using the for_each_... macro should make the code a bit shorter and
easier to read.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Set the DRIVER_ATOMIC flag to enable usage of the atomic updates API
with the driver.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

The field is set by drm_send_vblank_event(), there's no need to
preinitialize it.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

Plane state duplication takes a reference to the framebuffer stored in
the state, but state destroy doesn't release it. This causes a reference
leak. Fix it.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

The plane allocator has been inherently racy since the beginning of the
transition to atomic updates, as the allocator lock is released between
free plane check (at .atomic_check() time) and the reservation (at
.atomic_update() time).

To fix it, create a new allocator solely based on the atomic plane
states without keeping any external state and perform allocation in the
.atomic_check() handler. The core idea is to replace the free planes
bitmask with a collective knowledge based on the allocated hardware
plane(s) for each KMS plane. The allocator then loops over all plane
states to compute the free planes bitmask, allocates hardware planes
based on that bitmask, and stores the result back in the plane states.

For this to work we need to access the current state of planes not
touched by the atomic update. To ensure that it won't be modified, we
need to lock all planes using drm_atomic_get_plane_state(). This
effectively serializes atomic updates from .atomic_check() up to
completion, either when swapping the states if the check step has
succeeded, or when freeing the states if the check step has failed.

Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

Only the planes to CRTCs association control register DPTSR needs to be
protected by custom locking, don't hold the mutex around the whole code.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

As the DRM core will commit plane states when performing atomic updates,
those don't need to be committed manually when the CRTC is started except
in the system resume code path.

However, the atomic plane commit step is currently performed between
mode set disable and mode set enable to mimick the legacy mode setting
operations order. This causes the device clocks to be disabled after
applying plane settings and reenabled when enabling the CRTC,
potentially losing hardware in between.

Reorder the operations to enable the CRTC first and only then apply
plane settings, removing the need to manage clocks in the atomic begin
and flush handlers. We can then move the plane state commit code out of
the CRTC start handler to the system resume handler.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

The format stored in the rcar_du_plane structure is part of the plane
state. Move it to the rcar_du_plane_state structure and precompute it in
the .atomic_check() handler.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>

The rcar_du_crtc plane field is only used to check for an error that
can't occur. Remove it.

Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>