diff options
| author | Ville Syrjälä <ville.syrjala@linux.intel.com> | 2014-08-06 15:49:44 +0400 |
|---|---|---|
| committer | Daniel Vetter <daniel.vetter@ffwll.ch> | 2014-08-07 00:39:22 +0400 |
| commit | 7ffd7a68511c710b84db3548a1997fd2625f580a (patch) | |
| tree | f8b84573cb571663684d8d527348064e08737e44 /drivers/gpu/drm/drm_irq.c | |
| parent | 21d70354bba9965a098382fc4d7fb17e138111f3 (diff) | |
| download | linux-7ffd7a68511c710b84db3548a1997fd2625f580a.tar.xz | |
drm: Always reject drm_vblank_get() after drm_vblank_off()
Make sure drm_vblank_get() never succeeds when called between
drm_vblank_off() and drm_vblank_on(). Borrow a trick from the
old drm_vblank_{pre,post}_modeset() functions and just bump
the refcount in drm_vblank_off() and drop it in drm_vblank_on().
When drm_vblank_get() encounters a >0 refcount and the vblank
interrupt is already disabled it will simply return -EINVAL.
Hopefully the use of inmodeset won't conflict badly with
drm_vblank_{pre,post}_modeset().
For i915 there's a window between drm_vblank_off() and marking the
crtc as inactive where the current code still allows drm_vblank_get().
v2: Describe what drm_vblank_get() does to explain how
a simple refcount bump manages to fix things (Daniel)
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Diffstat (limited to 'drivers/gpu/drm/drm_irq.c')
| -rw-r--r-- | drivers/gpu/drm/drm_irq.c | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/drivers/gpu/drm/drm_irq.c b/drivers/gpu/drm/drm_irq.c index 0de123afdb34..b16a63622bad 100644 --- a/drivers/gpu/drm/drm_irq.c +++ b/drivers/gpu/drm/drm_irq.c @@ -1039,6 +1039,15 @@ void drm_vblank_off(struct drm_device *dev, int crtc) } spin_unlock(&dev->event_lock); + /* + * Prevent subsequent drm_vblank_get() from re-enabling + * the vblank interrupt by bumping the refcount. + */ + if (!dev->vblank[crtc].inmodeset) { + atomic_inc(&dev->vblank[crtc].refcount); + dev->vblank[crtc].inmodeset = 1; + } + spin_unlock_irqrestore(&dev->vbl_lock, irqflags); } EXPORT_SYMBOL(drm_vblank_off); @@ -1079,6 +1088,11 @@ void drm_vblank_on(struct drm_device *dev, int crtc) unsigned long irqflags; spin_lock_irqsave(&dev->vbl_lock, irqflags); + /* Drop our private "prevent drm_vblank_get" refcount */ + if (dev->vblank[crtc].inmodeset) { + atomic_dec(&dev->vblank[crtc].refcount); + dev->vblank[crtc].inmodeset = 0; + } /* re-enable interrupts if there's are users left */ if (atomic_read(&dev->vblank[crtc].refcount) != 0) WARN_ON(drm_vblank_enable(dev, crtc)); |