On Mon, 22 Aug 2011 11:05:31 -0700, Jesse Barnes <jbar...@virtuousgeek.org> wrote: > This fixes a race where we may try to finish a page flip and decrement > the refcount even if our vblank_get failed and we ended up with a > spurious flip pending interrupt. > > Fixes https://bugs.freedesktop.org/show_bug.cgi?id=34211. > > Signed-off-by: Jesse Barnes <jbar...@virtuousgeek.org> > > diff --git a/drivers/gpu/drm/i915/intel_display.c > b/drivers/gpu/drm/i915/intel_display.c > index 2319f62..0910537 100644 > --- a/drivers/gpu/drm/i915/intel_display.c > +++ b/drivers/gpu/drm/i915/intel_display.c > @@ -6896,6 +6896,10 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc, > work->old_fb_obj = intel_fb->obj; > INIT_WORK(&work->work, intel_unpin_work_fn); > > + ret = drm_vblank_get(dev, intel_crtc->pipe); > + if (ret) > + goto free_work; > + > /* We borrow the event spin lock for protecting unpin_work */ > spin_lock_irqsave(&dev->event_lock, flags); > if (intel_crtc->unpin_work) { > @@ -6906,6 +6910,11 @@ static int intel_crtc_page_flip(struct drm_crtc *crtc, > return -EBUSY;
You'll need a drm_vblank_put above this return. > } > intel_crtc->unpin_work = work; > + /* > + * Past this point, if we fail we'll let the flip completion code > + * clean up the vblank refcount and pin work. It'll be a spurious > + * completion, but we handle that case. > + */ I don't see how this is going to happen reliably; the hardware will have to generate a suitable interrupt, which on IRL and later will have to be an actual page flip interrupt. -- keith.pack...@intel.com
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