Writeback connectors represent writeback engines which can write the
CRTC output to a memory framebuffer. Add a writeback connector type and
related support functions.
Drivers should initialize a writeback connector with
drm_writeback_connector_init() which takes care of setting up all the
writeback-specific details on top of the normal functionality of
drm_connector_init().
Writeback connectors have a WRITEBACK_FB_ID property, used to set the
output framebuffer, and a WRITEBACK_PIXEL_FORMATS blob used to expose the
supported writeback formats to userspace.
When a framebuffer is attached to a writeback connector with the
WRITEBACK_FB_ID property, it is used only once (for the commit in which
it was included), and userspace can never read back the value of
WRITEBACK_FB_ID. WRITEBACK_FB_ID can only be set if the connector is
attached to a CRTC.
Changes since v1:
- Added drm_writeback.c + documentation
- Added helper to initialize writeback connector in one go
- Added core checks
- Squashed into a single commit
- Dropped the client cap
- Writeback framebuffers are no longer persistent
Changes since v2:
Daniel Vetter:
- Subclass drm_connector to drm_writeback_connector
- Relax check to allow CRTC to be set without an FB
- Add some writeback_ prefixes
- Drop PIXEL_FORMATS_SIZE property, as it was unnecessary
Gustavo Padovan:
- Add drm_writeback_job to handle writeback signalling centrally
Changes since v3:
- Rebased
- Rename PIXEL_FORMATS -> WRITEBACK_PIXEL_FORMATS
Chances since v4:
- Embed a drm_encoder inside the drm_writeback_connector to
reduce the amount of boilerplate code required from the drivers
that are using it.
Changes since v5:
- Added Rob Clark's atomic_commit() vfunc to connector helper
funcs, so that writeback jobs are committed from atomic helpers
- Updated create_writeback_properties() signature to return an
error code rather than a boolean false for failure.
- Free writeback job with the connector state rather than when
doing the cleanup_work()
Changes since v7:
- fix extraneous use of out_fence that is only introduced in a
subsequent patch.
Changes since v8:
- whitespace changes pull from subsequent patch
Changes since v9:
- Revert the v6 changes that free the writeback job in the connector
state cleanup and return to doing it in the cleanup_work() function
Signed-off-by: Brian Starkey <brian.starkey@arm.com>
[rebased and fixed conflicts]
Signed-off-by: Mihail Atanassov <mihail.atanassov@arm.com>
[rebased and added atomic_commit() vfunc for writeback jobs]
Signed-off-by: Rob Clark <robdclark@gmail.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Link: https://patchwork.freedesktop.org/patch/229037/
935774cd71