drm: Add writeback connector type
authorBrian Starkey <brian.starkey@arm.com>
Wed, 29 Mar 2017 16:42:32 +0000 (17:42 +0100)
committerLiviu Dudau <Liviu.Dudau@arm.com>
Wed, 20 Jun 2018 14:27:49 +0000 (15:27 +0100)
commit935774cd71fe604cc8ed24adcb507d7784255672
tree61aa8d66732c288df25d002c17620521b0900fa1
parentf664a52695429b68afb4e130a0f69cd5fd1fec86
drm: Add writeback connector type

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/
12 files changed:
Documentation/gpu/drm-kms.rst
drivers/gpu/drm/Makefile
drivers/gpu/drm/drm_atomic.c
drivers/gpu/drm/drm_atomic_helper.c
drivers/gpu/drm/drm_connector.c
drivers/gpu/drm/drm_writeback.c [new file with mode: 0644]
include/drm/drm_atomic.h
include/drm/drm_connector.h
include/drm/drm_mode_config.h
include/drm/drm_modeset_helper_vtables.h
include/drm/drm_writeback.h [new file with mode: 0644]
include/uapi/drm/drm_mode.h