Re: [RFC 0/9] nuclear pageflip

[Ben Widawsky <ben@bwidawsk.net>]

On Sun, 9 Sep 2012 22:19:59 -0500
Rob Clark <rob@ti.com> wrote:

> On Sun, Sep 9, 2012 at 10:03 PM, Rob Clark <rob.clark@linaro.org> wrote:
> > From: Rob Clark <rob@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.
> 

Can we please name this something different? I complained about this in
IRC, but I don't know if you hang around in #intel-gfx.

Some suggestions:
multiplane pageflip
muliplane atomic pageflip
atomic multiplane pageflip
atomic multiflip
pageflip of atomic and multiplane nature

Nuclear is not at all descriptive and requires as your response shows
:-)


> 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
> >
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-- 
Ben Widawsky, Intel Open Source Technology Center