[RFC 0/9] nuclear pageflip

[Rob Clark]

On Sun, Sep 9, 2012 at 10:03 PM, Rob Clark <rob.clark at linaro.org> wrote:
> From: Rob Clark <rob at ti.com>
>
> This is following a bit the approach that Ville is taking for atomic-
> modeset, in that it is switching over to using properties for everything.
> The advantage of this approach is that it makes it easier to add new
> attributes to set as part of a page-flip (and even opens the option to
> add new object types).

oh, and for those wondering what the hell this is all about,
nuclear-pageflip is a pageflip that atomically updates the CRTC layer
and zero or more attached plane layers, optionally changing various
properties such as z-order (or even blending modes, etc) atomically.
It includes the option for a test step so userspace compositor can
test a proposed configuration (if any properties not marked as
'dynamic' are updated).  This intended to allow, for example, weston
compositor to synchronize updates to plane (sprite) layers with CRTC
layer.

BR,
-R

> The basic principles are:
>  a) split out object state (in this case, plane and crtc, although I
>     expect more to be added as atomic-modeset is added) into seperate
>     structures that can be atomically commited or rolled back
>  b) expand the object property API (set_property()) to take a state
>     object.  The obj->set_property() simply updates the state object
>     without actually applying the changes to the hw.
>  c) after all the property updates are done, the updated state can
>     be checked for correctness and against the hw capabilities, and
>     then either discarded or committed atomically.
>
> Since we need to include properties in the nuclear-pageflip scheme,
> doing everything via properties avoids updating a bunch of additional
> driver provided callbacks.  Instead we just drop crtc->page_flip()
> and plane->update_plane().  By splitting out the object's mutable
> state into drm_{plane,crtc,etc}_state structs (which are wrapped by
> the individual drivers to add their own hw specific state), we can
> use some helpers (drm_{plane,crtc,etc}_set_property() and
> drm_{plane,crtc,etc}_check_state()) to keep core error checking in
> drm core and avoid pushing the burden of dealing with common
> properties to the individual drivers.
>
> So far, I've only updated omapdrm to the new APIs, as a proof of
> concept.  Only a few drivers support drm plane, so I expect the
> updates to convert drm-plane to properties should not be so hard.
> Possibly for crtc/pageflip we might need to have a transition period
> where we still support crtc->page_flip() code path until all drivers
> are updated.
>
> My complete branch is here:
>
>   https://github.com/robclark/kernel-omap4/commits/drm_nuclear
>   git://github.com/robclark/kernel-omap4.git drm_nuclear
>
> Rob Clark (9):
>   drm: add atomic fxns
>   drm: add object property type
>   drm: add DRM_MODE_PROP_DYNAMIC property flag
>   drm: convert plane to properties
>   drm: add drm_plane_state
>   drm: convert page_flip to properties
>   drm: add drm_crtc_state
>   drm: nuclear pageflip
>   drm/omap: update for atomic age
>
>  drivers/gpu/drm/drm_crtc.c            |  769 +++++++++++++++++++++++----------
>  drivers/gpu/drm/drm_crtc_helper.c     |   51 +--
>  drivers/gpu/drm/drm_drv.c             |    1 +
>  drivers/gpu/drm/drm_fb_helper.c       |   11 +-
>  drivers/staging/omapdrm/Makefile      |    1 +
>  drivers/staging/omapdrm/omap_atomic.c |  270 ++++++++++++
>  drivers/staging/omapdrm/omap_atomic.h |   52 +++
>  drivers/staging/omapdrm/omap_crtc.c   |  247 +++++------
>  drivers/staging/omapdrm/omap_drv.c    |    5 +
>  drivers/staging/omapdrm/omap_drv.h    |   35 +-
>  drivers/staging/omapdrm/omap_fb.c     |   44 +-
>  drivers/staging/omapdrm/omap_plane.c  |  270 ++++++------
>  include/drm/drm.h                     |    2 +
>  include/drm/drmP.h                    |   32 ++
>  include/drm/drm_crtc.h                |  140 ++++--
>  include/drm/drm_mode.h                |   48 ++
>  16 files changed, 1378 insertions(+), 600 deletions(-)
>  create mode 100644 drivers/staging/omapdrm/omap_atomic.c
>  create mode 100644 drivers/staging/omapdrm/omap_atomic.h
>
> --
> 1.7.9.5
>