On 2019-07-26 11:06 p.m., Sam Ravnborg wrote: > DRM_WAIT_ON() is from the deprecated drm_os_linux header and > the modern replacement is the wait_event_*. > > The return values differ, so a conversion is needed to > keep the original interface towards userspace. > Introduced a switch/case to make code obvious. > > Analysis from Michel Dänzer: > > The waiting condition rely on all relevant places where vblank_count > is modified calls wake_up(&vblank->queue). > > drm_handle_vblank(): > - Calls wake_up(&vblank->queue) > > drm_vblank_enable(): > - There is no need here because there can be no sleeping waiters > in the queue, because vblank->enabled == false immediately > terminates any waits. > > drm_crtc_accurate_vblank_count(): > - This is called from interrupt handlers, at least from > amdgpu_dm.c:dm_pflip_high_irq(). Not sure it needs to wake up > the queue though, the driver should call > drm_(crtc_)_handle_vblank anyway. > > drm_vblank_disable_and_save(): > - It can be called from an interrupt, via drm_handle_vblank -> > vblank_disable_fn. However, the only place where > drm_vblank_disable_and_save can be called with sleeping waiters > in the queue is in drm_crtc_vblank_off, which wakes up the queue > afterwards (which terminates all waits, because > vblank->enabled == false at this point). > > v3: > - Added analysis to changelog from Michel Dänzer > - Moved return result handling inside if (req_seq != seq) (Daniel V) > - Reused more of the former logic - resulting in simpler code > - Dropped Reviewed-by from Sean Paul as this is a new implmentation > > v2: > - Fix so the case where req_seq equals seq was handled properly > - quick hack to check if IGT became happy > - Only sent to igt, not to dri-devel > > Signed-off-by: Sam Ravnborg <sam@xxxxxxxxxxxx> > Cc: "Michel Dänzer" <michel@xxxxxxxxxxx> > Cc: Sean Paul <sean@xxxxxxxxxx> > Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx> > Cc: Maxime Ripard <maxime.ripard@xxxxxxxxxxx> > Cc: David Airlie <airlied@xxxxxxxx> > Cc: Daniel Vetter <daniel@xxxxxxxx> Reviewed-by: Michel Dänzer <michel.daenzer@xxxxxxx> -- Earthling Michel Dänzer | https://www.amd.com Libre software enthusiast | Mesa and X developer _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
