[Nouveau] [PATCH] drm/nouveau: handle same-fb page flips

[Marcin Ślusarz]

17 paź 2012 06:31, "Ben Skeggs" <skeggsb at gmail.com> napisał(a):
>
> On Fri, Oct 05, 2012 at 09:37:59PM +0200, Marcin Slusarz wrote:
> > It's questionable use case, but weston/wayland already relies on this
behaviour,
> > and other drivers don't care about it, so it's a matter of
compatibility.
> > Without it, process invoking such page flip hangs in unkillable state,
trying
> > to reserve the same buffer twice.
> >
> > Signed-off-by: Marcin Slusarz <marcin.slusarz at gmail.com>
> > ---
> >  drivers/gpu/drm/nouveau/nouveau_display.c | 20 +++++++++++++++-----
> >  1 file changed, 15 insertions(+), 5 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/nouveau/nouveau_display.c
b/drivers/gpu/drm/nouveau/nouveau_display.c
> > index 61f370d..a52cfd3 100644
> > --- a/drivers/gpu/drm/nouveau/nouveau_display.c
> > +++ b/drivers/gpu/drm/nouveau/nouveau_display.c
> > @@ -530,9 +530,11 @@ nouveau_page_flip_reserve(struct nouveau_bo
*old_bo,
> >       if (ret)
> >               goto fail;
> >
> > -     ret = ttm_bo_reserve(&old_bo->bo, false, false, false, 0);
> > -     if (ret)
> > -             goto fail_unreserve;
> > +     if (likely(old_bo != new_bo)) {
> > +             ret = ttm_bo_reserve(&old_bo->bo, false, false, false, 0);
> > +             if (ret)
> > +                     goto fail_unreserve;
> > +     }
> >
> >       return 0;
> >
> > @@ -551,8 +553,10 @@ nouveau_page_flip_unreserve(struct nouveau_bo
*old_bo,
> >       nouveau_bo_fence(new_bo, fence);
> >       ttm_bo_unreserve(&new_bo->bo);
> >
> > -     nouveau_bo_fence(old_bo, fence);
> > -     ttm_bo_unreserve(&old_bo->bo);
> > +     if (likely(old_bo != new_bo)) {
> > +             nouveau_bo_fence(old_bo, fence);
> > +             ttm_bo_unreserve(&old_bo->bo);
> > +     }
> >
> >       nouveau_bo_unpin(old_bo);
> >  }
> > @@ -624,6 +628,12 @@ nouveau_crtc_page_flip(struct drm_crtc *crtc,
struct drm_framebuffer *fb,
> >       if (!drm->channel)
> >               return -ENODEV;
> >
> > +     if (unlikely(old_bo == new_bo)) {
> > +             char name[sizeof(current->comm)];
> > +             pr_debug_ratelimited("'%s': useless page flip invoked\n",
> > +                             get_task_comm(name, current));
> > +     }
> > +
> The patch looks alright, except I think we should just drop this hunk,
> no other driver reports it either.
>
> Thoughts?

It will be easier to debug buggy clients with this code in. With multiple
wayland compositors it's possible some of them might be buggy... But I
don't feel strongly about it. You can delete this hunk when applying.

Marcin
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