On Wed, Jul 30, 2014 at 05:36:21PM +0300, Ville Syrj?l? wrote: > On Wed, Jul 30, 2014 at 04:20:25PM +0200, Thierry Reding wrote: > > On Wed, Jul 30, 2014 at 05:32:28PM +0900, Michel D?nzer wrote: > > > On 30.07.2014 17:22, Daniel Vetter wrote: > > > > On Wed, Jul 30, 2014 at 11:59:33AM +0900, Michel D?nzer wrote: > > > >> On 30.07.2014 06:32, Daniel Vetter wrote: > > > >>> + * due to lack of driver support or because the crtc is off. > > > >>> + */ > > > >>> +void drm_crtc_vblank_wait(struct drm_crtc *crtc) > > > >>> +{ > > > >>> + drm_vblank_wait(crtc->dev, drm_crtc_index(crtc)); > > > >>> +} > > > >>> +EXPORT_SYMBOL(drm_crtc_vblank_wait); > > > >>> + > > > >>> +/** > > > >> > > > >> Maybe the function names should be *_vblank_wait_next() or something to > > > >> clarify the purpose and reduce potential confusion versus > > > >> drm_wait_vblank(). > > > > > > > > Yeah that name is just transferred from the i915 driver. What about > > > > drm_wait_one_vblank()/drm_crtc_wait_one_vblank()? > > > > > > I don't care that much :), go ahead. > > > > Just my two cents: our downstream kernel has a helper somewhat like this > > which waits for a specified number of frames (apparently this is useful > > for some panels that require up to 5 or 6 frames before they display the > > correct image on screen). So perhaps something like this could work: > > > > void drm_wait_vblank_count(struct drm_device *dev, unsigned int crtc, > > unsigned int count) > > { > > u32 last; > > int ret; > > > > ret = drm_vblank_get(dev, crtc); > > if (WARN_ON(ret)) > > return; > > > > while (count--) { > > last = drm_vblank_count(dev, crtc); > > > > ... > > } > > > > drm_vblank_put(dev, crtc); > > } > > Would be nicer to wait for an absolute vblank count instead IMO. Or > if you want to pass a relative count in just convert it to an absolute > count first and wait for it (taking wraparound into account obviously).
Hmm... would something like this work? target = drm_vblank_count(dev, crtc) + count; ret = wait_event_timeout(..., drm_vblank_count(dev, crtc) == target, ...); That should properly take into account wrap-around given that both sites use drm_vblank_count(). Thierry -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 819 bytes Desc: not available URL: <http://lists.freedesktop.org/archives/dri-devel/attachments/20140730/80a0d01c/attachment.sig>