drm: Refactor setplane to allow internal use (v3)

Refactor DRM setplane code into a new setplane_internal() function that
takes DRM objects directly as parameters rather than looking them up by
ID.  We'll use this in a future patch when we implement legacy cursor
ioctls on top of the universal plane interface.

v3:
 - Move integer overflow checking from setplane_internal to setplane
   ioctl.  The upcoming legacy cursor support via universal planes needs
   to maintain current cursor ioctl semantics and not return error for
   these extreme values (found via intel-gpu-tools kms_cursor_crc test).
v2:
 - Allow planes to be disabled without a valid crtc again (and add
   mention of this to setplane's kerneldoc, since it doesn't seem to be
   mentioned anywhere else).
 - Reformat some parameter line wrap

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
drm: Support legacy cursor ioctls via universal planes when possible (v4)

If drivers support universal planes and have registered a cursor plane
with the DRM core, we should use that universal plane support when
handling legacy cursor ioctls.  Drivers that transition to universal
planes won't have to maintain separate legacy ioctl handling; drivers
that don't transition to universal planes will continue to operate
without any change to behavior.

Note that there's a bit of a mismatch between the legacy cursor ioctls
and the universal plane API's --- legacy ioctl's use driver buffer
handles directly whereas the universal plane API takes drm_framebuffers.
Since there's no way to recover the driver handle from a
drm_framebuffer, we can implement legacy ioctl's in terms of universal
plane interfaces, but cannot implement universal plane interfaces in
terms of legacy ioctls.  Specifically, there's no way to create a
general cursor helper in the way we previously created a primary plane
helper.

It's important to land this patch before any patches that add universal
cursor support to individual drivers so that drivers don't have to worry
about juggling two different styles of reference counting for cursor
buffers when userspace mixes and matches legacy and universal cursor
calls.  With this patch, a driver that switches to universal cursor
support may assume that all cursor buffers are wrapped in a
drm_framebuffer and can rely on framebuffer reference counting for all
cursor operations.

v4:
 - Add comments pointing out setplane_internal's reference-eating
   semantics.
v3:
 - Drop drm_mode_rmfb() call that is no longer needed now that we're
   using setplane_internal(), which takes care of deref'ing the
   appropriate framebuffer.
v2:
 - Use new add_framebuffer_internal() function to create framebuffer
   rather than trying to call directly into the ioctl interface and
   look up the handle returned.
 - Use new setplane_internal() function to update the cursor plane
   rather than calling through the ioctl interface.  Note that since
   we're no longer looking up an fb_id, no extra reference will be
   taken here.
 - Grab extra reference to fb under lock in !BO case to avoid issues
   where racing userspace could cause the fb to be destroyed out from
   under us after we grab the fb pointer.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
drm: Allow drivers to register cursor planes with crtc

Universal plane support had placeholders for cursor planes, but didn't
actually do anything with them.  Save the cursor plane reference inside
the crtc and update the cursor plane parameter from void* to drm_plane.

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
drm/i915: Add intel_crtc_cursor_set_obj() to set cursor buffer (v2)

Refactor cursor buffer setting such that the code to actually update the
cursor lives in a new function, intel_crtc_cursor_set_obj(), and takes
a GEM object as a parameter.  The existing legacy cursor ioctl handler,
intel_crtc_cursor_set() will now perform the userspace handle lookup and
then call this new function.

This refactoring is in preparation for the universal plane cursor
support where we'll want to update the cursor with an actual GEM buffer
object (obtained via drm_framebuffer) rather than a userspace handle.

v2:  Drop obvious kerneldoc and replace with note about function's
     reference consumption

Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
drm/i915: Switch to unified plane cursor handling (v4)

The DRM core will translate calls to legacy cursor ioctls into universal
cursor calls automatically, so there's no need to maintain the legacy
cursor support.  This greatly simplifies the transition since we don't
have to handle reference counting differently depending on which cursor
interface was called.

The aim here is to transition to the universal plane interface with
minimal code change.  There's a lot of cleanup that can be done (e.g.,
using state stored in crtc->cursor->fb rather than intel_crtc) that is
left to future patches.

v4:
 - Drop drm_gem_object_unreference() that is no longer needed now that
   we receive the GEM obj directly rather than looking up the ID.
v3:
 - Pass cursor obj to intel_crtc_cursor_set_obj() if cursor fb changes,
   even if 'visible' is false.  intel_crtc_cursor_set_obj() will notice
   that the cursor isn't visible and disable it properly, but we still
   need to get intel_crtc->cursor_addr set properly so that we behave
   properly if the cursor becomes visible again in the future without
   changing the cursor buffer (noted by Chris Wilson and verified
   via i-g-t kms_cursor_crc).
 - s/drm_plane_init/drm_universal_plane_init/.  Due to type
   compatibility between enum and bool, everything actually works
   correctly with the wrong init call, except for the type of plane that
   gets exposed to userspace (it shows up as type 'primary' rather than
   type 'cursor').
v2:
 - Remove duplicate dimension checks on cursor
 - Drop explicit cursor disable from crtc destroy (fb & plane
   destruction will take care of that now)
 - Use DRM plane helper to check update parameters

Cc: intel-gfx@lists.freedesktop.org
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>