Re: [PATCH] drm/rockchip: Return -EBUSY if there's already a pending flip event v3

Hi Tomeu,

On 4 April 2016 at 14:55, Tomeu Vizoso tomeu.vizoso@collabora.com wrote:

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_fb.c b/drivers/gpu/drm/rockchip/rockchip_drm_fb.c index 3b8f652698f8..8305bbd2a4d7 100644 --- a/drivers/gpu/drm/rockchip/rockchip_drm_fb.c +++ b/drivers/gpu/drm/rockchip/rockchip_drm_fb.c @@ -280,7 +280,18 @@ int rockchip_drm_atomic_commit(struct drm_device *dev, { struct rockchip_drm_private *private = dev->dev_private; struct rockchip_atomic_commit *commit = &private->commit;

•   int ret;
  

•   struct drm_crtc_state *crtc_state;
  

•   struct drm_crtc *crtc;
  

•   int i, ret;
  

•   if (async) {
  

•           for_each_crtc_in_state(state, crtc, crtc_state, i) {
  

•                   if (crtc->state->event ||
  

•                       rockchip_drm_crtc_has_pending_event(crtc)) {
  

•                           return -EBUSY;
  

•                   }
  

•           }
  

•   }
  

Hmmm ...

Doesn't this trigger before the VOP atomic_begin() helper, meaning that anything with an event set will trigger the check? Seems like it should be && rather than ||.

Also, I know rockchip_drm_vop.c isn't holding dev->event_lock when it checks vop->event, but it really should be ... and so should this check. Otherwise you can race with the IRQ handler, which isn't required to hold the CRTC lock.

Cheers, Daniel