Re: [PATCH 01/11] drm: add plane support

[Jesse Barnes <jbarnes@virtuousgeek.org>]

On Tue, 25 Oct 2011 14:26:07 +0100
Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:

> > As discussed with Jesse on irc, drm fb handling is fragile. Current
> > rules:
> > - fbs are not reference counted, hence when destroying we need to
> > disable all crtcs (and now also planes) that use them.
> > drm_framebuffer_cleanup does that atm
> > - drivers that hold onto fbs after the kms core drops the
> > corresponding pointer needs to hold a ref onto the underlying
> > backing storage (like e.g. for pageflip on the to-be-flipped-out fb
> > as long as it might still be scanned out).
> > 
> > We need proper refcounting for these ... But for now this patch is
> > missing the plane cleanup in drm_framebuffer_cleanup.
> 
> I'd rather we fixed the framebuffer kref stuff as part of doing this
> rather than have a poorer API because of something we have to fix
> anyway.
> 
> It shouldn't be *that* hard to fix, at least for this kind of use
> case. Resize locking, fb moving etc are ugly issues, refcount
> shouldn't be, and the tty layer also refcounts so we can only have
> the fb objects themselves to worry about as we can defer fb
> destruction to tty close or drm last unref even for those with
> consoles on them.

Oh it doesn't affect the userspace API so I don't think it's urgent.
But I agree, it would be nice to clean up fb management a bit...  Any
volunteers? :)

Thanks,
Jesse