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).
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. The property values array is also split out into the state structs, so that the property values visible to userspace automatically reflect the current state (ie. property changes are either committed or discarded depending on whether the state changes are committed or discarded). 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 atomic-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.
The intention is for this to also simplify atomic-modeset, by providing some of the necessary infrastructure (object property types, signed property values, and property's whose usespace visible values automatically tracks the object state which is either committed or discarded depending on whether the state change was committed to hw or not) which will also be needed for atomic-modeset.
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
Open points (I think) are: + should atomic-pageflip support flips on multiple CRTCs. I think it at least simplifies things if the driver knows up front which CRTC(s) are involved, and whether the operation is modeset (sync) or pageflip (async). + How to deal w/ hardware restrictions which span multiple CRTCs. One idea is to get rid of the test flag in the atomic-pageflip ioctl, and always do test operations via atomic-modeset ioctl w/ the test flag.
Rob Clark (11): drm: add atomic fxns drm: add object property type drm: add DRM_MODE_PROP_DYNAMIC property flag drm: add DRM_MODE_PROP_SIGNED property flag drm: split property values out drm: convert plane to properties drm: add drm_plane_state drm: convert page_flip to properties drm: add drm_crtc_state drm: atomic pageflip drm/omap: update for atomic age
drivers/gpu/drm/drm_crtc.c | 838 ++++++++++++++++++++++++--------- 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 | 339 +++++++++++++ drivers/staging/omapdrm/omap_atomic.h | 52 ++ drivers/staging/omapdrm/omap_crtc.c | 246 +++++----- drivers/staging/omapdrm/omap_drv.c | 21 +- drivers/staging/omapdrm/omap_drv.h | 45 +- drivers/staging/omapdrm/omap_fb.c | 44 +- drivers/staging/omapdrm/omap_plane.c | 296 ++++++------ include/drm/drm.h | 2 + include/drm/drmP.h | 52 ++ include/drm/drm_crtc.h | 179 +++++-- include/drm/drm_mode.h | 50 ++ 16 files changed, 1607 insertions(+), 621 deletions(-) create mode 100644 drivers/staging/omapdrm/omap_atomic.c create mode 100644 drivers/staging/omapdrm/omap_atomic.h