Hi Michael. On Fri, Jul 19, 2019 at 11:05:44AM +0200, Michel Dänzer wrote: > On 2019-07-19 8:07 a.m., Sam Ravnborg wrote: > > On Thu, Jul 18, 2019 at 05:37:31PM +0200, Sam Ravnborg wrote: > >> This is some janitorial updates to the via driver > >> that is required to get rid of deprecated headers > >> in the drm subsystem. > >> > >> The first three patches are trivial, where > >> the dependencies on drmP.h and drm_os_linux are dropped. > >> > >> The remaining three patches drop use of DRM_WAIT_ON(). > >> They are replaced by wait_event_interruptible_timeout(). > >> These patches could use a more critical review. > > > > The differences between DRM_WAIT_ON() and > > wait_event_interruptible_timeout() are bigger than anticipated. > > > > The conversion I did for drm_vblank.c is bogus thus I expect > > the conversion done for via is also bogus. > > What exactly is the problem though? Can you share information about the > failures you're seeing? > > There was some discussion about DRM_WAIT_ON() "polling" on IRC. I assume > that refers to it only sleeping for up to 0.01s before checking the > condition again. In contrast, wait_event_interruptible_timeout() checks > the condition once, then sleeps up to the full timeout before checking > it again. Correct - it was based on the feedback on irc from airlied and ickle that made me conclude that the via part may not be good. I cannot say if the polling versus timeout is properly dealt with in the via driver and I am inclided to just move DRM_WAIT_ON() to via_drv.h and name it VIA_WAIT_ON(). Then the changes to this legacy driver is minimal and it will not prevent us from gettting rid of drm_os_linux.h > > If that makes a difference for drm_wait_vblank_ioctl, it indicates that > some other code which updates the vblank count or clears vblank->enabled > doesn't wake up the vblank->queue. Let me analyse a little... In drm_handle_vblank() there is a call to wake_up(&vblank->queue); And this is called from an interrupt - OK. drm_vblank_enable() is called outside an interrupt - no need for wake_up() drm_crtc_accurate_vblank_count() is called outside interrupt - no need for wake_up() drm_vblank_disable_and_save() is called outside interrupt - no need for wake_up()' That is all functions I could dig up that updates the vblank counter. So based on this short analysis I actually start to think that I can use the variant that uses wait_event_interruptible_timeout() anyway. I will post a v3 and await feedback on that version. As for via - introducing VIA_WAIT_ON() is the simple solution. So I will post a v2 of this series using VIA_WAIT_ON(). Sam _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
