drm/omap: protect omap_crtc's event with event_lock spinlock

The vblank_cb callback and the page_flip ioctl can occur together in different
CPU contexts. vblank_cb uses takes tje drm device's event_lock spinlock when
sending the vblank event and updating omap_crtc->event and omap_crtc->od_fb.

Use the same spinlock in page_flip, to make sure the above omap_crtc parameters
are configured sequentially.

Signed-off-by: Archit Taneja <archit@ti.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/drivers/gpu/drm/omapdrm/omap_crtc.c b/drivers/gpu/drm/omapdrm/omap_crtc.c
index 00798247190b..e3c47a8005ff 100644
--- a/drivers/gpu/drm/omapdrm/omap_crtc.c
+++ b/drivers/gpu/drm/omapdrm/omap_crtc.c
@@ -350,11 +350,15 @@ static int omap_crtc_page_flip_locked(struct drm_crtc *crtc,
         struct omap_crtc *omap_crtc = to_omap_crtc(crtc);
         struct drm_plane *primary = crtc->primary;
         struct drm_gem_object *bo;
+        unsigned long flags;
 
         DBG("%d -> %d (event=%p)", primary->fb ? primary->fb->base.id : -1,
                         fb->base.id, event);
 
+        spin_lock_irqsave(&dev->event_lock, flags);
+
         if (omap_crtc->old_fb) {
+                spin_unlock_irqrestore(&dev->event_lock, flags);
                 dev_err(dev->dev, "already a pending flip\n");
                 return -EINVAL;
         }
@@ -362,6 +366,8 @@ static int omap_crtc_page_flip_locked(struct drm_crtc *crtc,
         omap_crtc->event = event;
         omap_crtc->old_fb = primary->fb = fb;
 
+        spin_unlock_irqrestore(&dev->event_lock, flags);
+
         /*
          * Hold a reference temporarily until the crtc is updated
          * and takes the reference to the bo.  This avoids it