On Wed, Sep 12, 2012 at 12:35:01PM -0500, Rob Clark wrote:
> On Wed, Sep 12, 2012 at 11:57 AM, Jesse Barnes <jbarnes@xxxxxxxxxxxxxxxx> wrote:
> > On Sun, 9 Sep 2012 22:03:14 -0500
> > Rob Clark <rob.clark@xxxxxxxxxx> wrote:
> >
> >> From: Rob Clark <rob@xxxxxx>
> >>
> >> The 'atomic' mechanism allows for multiple properties to be updated,
> >> checked, and commited atomically. This will be the basis of atomic-
> >> modeset and nuclear-pageflip.
> >>
> >> The basic flow is:
> >>
> >> state = dev->atomic_begin();
> >> for (... one or more ...)
> >> obj->set_property(obj, state, prop, value);
> >> if (dev->atomic_check(state))
> >> dev->atomic_commit(state, event);
> >> dev->atomic_end(state);
> >
> > I think the above is more suited to drm_crtc_helper code. I think the
> > top level callback should contain the arrays and be a single "multi
> > flip" hook (or maybe a check then set double callback). For some
> > drivers that'll end up being a lot simpler, rather than sprinkling
> > atomic handling code in all the set_property callbacks.
>
> well, there are a few other places in drm_crtc.c where I want to use
> the new API, to avoid drivers having to support both atomic API and
> old set_plane/page_flip stuff.. the transactional API makes that a bit
> easier, I think.. or at least I don't have to construct an array on
> the stack.
Usually you would need to build up the full state anyway before you can
tell if it's good or bad. I don't see what some big array would buy here.
> > Having a transactional API just seems a little messier with both the
> > atomic state and per-property state to track and rollback in the case
> > of failure.
>
> For the rollback, I think I'm just going to move the array of property
> values into drm_{crtc,plane,etc}_state. That way, userspace doesn't
> see updated property values if they are not committed. It makes the
> property value rollback automatic.
This was my original idea as well. Separate the current and future
states cleanly. At the moment it's all mixed up inside the objects
somewhere. I sort of abandoned the idea so that I could avoid touching
too much driver code while prototyping the atomic modesetting, but
that's certainly the way I would design the system.
--
Ville Syrjälä
Intel OTC
_______________________________________________
dri-devel mailing list
dri-devel@xxxxxxxxxxxxxxxxxxxxx
http://lists.freedesktop.org/mailman/listinfo/dri-devel
