new userspace API approaches atomic *

[Rob Clark]

On Thu, Dec 13, 2012 at 3:13 PM, Dave Airlie <airlied at gmail.com> wrote:
> So this is a how to get new features pronouncement,
>
> From what I can see people would like to have atomic interfaces for
> pageflip and modesetting merged,
>
> Now how I think developing and merging these will work (i.e. do it
> this way or don't bother)
>
> a) get an API you are happy with working, it doesn't need to be perfect
>
> b) rework the internal drm core/driver APIs for all drivers to allow
> this new interface to be used. Remove
> the old internal apis and create an interface layer between the old
> userspace interface and the new API.

fwiw, I had started to do this w/ my atomic series.. what I did was to
keep (for example) old .page_flip(), as a legacy path so we didn't
have to merge changes for all drivers in one shot, but the idea was
to, after all drivers are updated, to remove the legacy paths.

The userspace API for atomic pageflip is really a small part of the
whole thing.  The bigger thing is atomic fxns and property conversion.
 So we could even leave off the new userspace API for now.  Probably
the addition of the new ioctl(s) should be the last part.

I had started merging my changes w/ Ville's changes.  I got a bit
distracted on writing a new kms driver (should have RFC to send for
that, hopefully this afternoon).. but hopefully should have some more
time to spend on this RSN..

BR,
-R

> c) throw away (a)
>
> d) reimplement a userspace API on top of the new internal driver API
> fixing all the things you have learned,
> were crazy, insane, nuts etc.
>
> e) have a lot of tests.
>
> f) get b merged standalone, transition phase is fine, but every driver
> needs to be ported before the API
> goes in.
>
> g) throw away d
>
> h) write final API and get it merged.
>
> Yes this is probably more work than you or your manager is willing to
> buy in, but then maybe the feature isn't that important.
>
> Dave.
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