[PATCH 08/20] drm/armada: use xchg() to atomically update dplane->old_fb

[Russell King - ARM Linux]

On Wed, Sep 30, 2015 at 11:49:44AM +0100, Emil Velikov wrote:
> Hi Russell,
> 
> On 29 September 2015 at 19:10, Russell King <rmk+kernel at arm.linux.org.uk> wrote:
> > Rather than using a spinlock, use xchg() to atomically update
> > dplane->old_fb.  This allows us to eliminate dplane->lock.
> >
> > Signed-off-by: Russell King <rmk+kernel at arm.linux.org.uk>
> > ---
> [...]
> > @@ -76,13 +75,10 @@ static void armada_ovl_retire_fb(struct armada_ovl_plane *dplane,
> >  {
> >         struct drm_framebuffer *old_fb;
> >
> > -       spin_lock(&dplane->lock);
> > -       old_fb = dplane->old_fb;
> > -       dplane->old_fb = fb;
> > -       spin_unlock(&dplane->lock);
> > +       old_fb = xchg(&dplane->old_fb, fb);
> >
> >         if (old_fb)
> > -               armada_drm_queue_unref_work(dplane->base.dev, old_fb);
> > +               armada_drm_queue_unref_work(dplane->base.base.dev, old_fb);
> Shouldn't this be part of another patch ?

Yes, you're right, it should be in:

drm/armada: introduce generic armada_plane struct

Now moved there, thanks.

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