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Re: [PATCH 3/3] drm: Add CRTC_GET_SEQUENCE and CRTC_QUEUE_SEQUENCE ioctls

From Ville Syrjälä <ville.syrjala@linux.intel.com>
Newsgroups linux.kernel
Subject Re: [PATCH 3/3] drm: Add CRTC_GET_SEQUENCE and CRTC_QUEUE_SEQUENCE ioctls
Date 2017-07-06 16:10 +0200
Message-ID <u0fDI-5sz-23@gated-at.bofh.it> (permalink)
References <u00Ol-3Tl-5@gated-at.bofh.it> <u00Om-3Tl-15@gated-at.bofh.it> <u09RD-1qm-7@gated-at.bofh.it> <u0c38-2WU-25@gated-at.bofh.it> <u0cPw-3uf-25@gated-at.bofh.it>
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On Thu, Jul 06, 2017 at 01:04:18PM +0200, Daniel Vetter wrote:
> On Thu, Jul 6, 2017 at 12:16 PM, Ville Syrjälä
> <ville.syrjala@linux.intel.com> wrote:
> >> > +   if (!dev->irq_enabled)
> >> > +           return -EINVAL;
> >> > +
> >> > +   crtc = drm_crtc_find(dev, get_seq->crtc_id);
> >> > +   if (!crtc)
> >> > +           return -ENOENT;
> >> > +
> >> > +   pipe = drm_crtc_index(crtc);
> >> > +
> >> > +   get_seq->sequence = drm_vblank_count_and_time(dev, pipe, &now);
> >>
> >> This can give you and old vblank if the vblank is off (i.e. sw state
> >> hasn't be regularly updated). I think we want a new
> >> drm_crtc_accurate_vblank_count_and_time variant.
> >
> > Or better yet just do what Chris did for the old ioctl in commit
> > b33b02707ba3 ("drm: Peek at the current counter/timestamp for vblank queries")
> 
> Yeah the READ_ONCE(vblank->enabled) is a nice fastpath. But we still
> need the accurate one as slowpath in case the vblank irq is off.

Maybe, or maybe we want to turn the interrupt on in that case? That's
what the old ioctl does.

-- 
Ville Syrjälä
Intel OTC

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Thread

[PATCH 0/3] drm: Add CRTC-id based ioctls for vblank query/event Keith Packard <keithp@keithp.com> - 2017-07-06 00:20 +0200
  [PATCH 1/3] drm: Widen vblank count to 64 bits. Change vblank time precision to ns Keith Packard <keithp@keithp.com> - 2017-07-06 00:20 +0200
    Re: [PATCH 1/3] drm: Widen vblank count to 64 bits. Change vblank  time precision to ns Daniel Vetter <daniel@ffwll.ch> - 2017-07-06 09:30 +0200
      Re: [PATCH 1/3] drm: Widen vblank count to 64 bits. Change vblank time precision to ns Keith Packard <keithp@keithp.com> - 2017-07-06 17:10 +0200
        Re: [PATCH 1/3] drm: Widen vblank count to 64 bits. Change vblank  time precision to ns Daniel Vetter <daniel@ffwll.ch> - 2017-07-07 14:20 +0200
    Re: [PATCH 1/3] drm: Widen vblank count to 64 bits. Change vblank  time precision to ns Michel Dänzer <michel@daenzer.net> - 2017-07-06 09:50 +0200
      Re: [PATCH 1/3] drm: Widen vblank count to 64 bits. Change vblank  time precision to ns Michel Dänzer <michel@daenzer.net> - 2017-07-06 10:10 +0200
        Re: [PATCH 1/3] drm: Widen vblank count to 64 bits. Change vblank time precision to ns Keith Packard <keithp@keithp.com> - 2017-07-06 17:20 +0200
      Re: [PATCH 1/3] drm: Widen vblank count to 64 bits. Change vblank time precision to ns Keith Packard <keithp@keithp.com> - 2017-07-06 17:10 +0200
        Re: [PATCH 1/3] drm: Widen vblank count to 64 bits. Change vblank  time precision to ns Michel Dänzer <michel@daenzer.net> - 2017-07-07 03:40 +0200
          Re: [PATCH 1/3] drm: Widen vblank count to 64 bits. Change vblank  time precision to ns Michel Dänzer <michel@daenzer.net> - 2017-07-07 04:10 +0200
  [PATCH 3/3] drm: Add CRTC_GET_SEQUENCE and CRTC_QUEUE_SEQUENCE ioctls Keith Packard <keithp@keithp.com> - 2017-07-06 00:20 +0200
    Re: [PATCH 3/3] drm: Add CRTC_GET_SEQUENCE and CRTC_QUEUE_SEQUENCE  ioctls Daniel Vetter <daniel@ffwll.ch> - 2017-07-06 10:00 +0200
      Re: [PATCH 3/3] drm: Add CRTC_GET_SEQUENCE and CRTC_QUEUE_SEQUENCE  ioctls Ville Syrjälä <ville.syrjala@linux.intel.com> - 2017-07-06 12:20 +0200
        Re: [PATCH 3/3] drm: Add CRTC_GET_SEQUENCE and CRTC_QUEUE_SEQUENCE ioctls Daniel Vetter <daniel@ffwll.ch> - 2017-07-06 13:10 +0200
          Re: [PATCH 3/3] drm: Add CRTC_GET_SEQUENCE and CRTC_QUEUE_SEQUENCE  ioctls Ville Syrjälä <ville.syrjala@linux.intel.com> - 2017-07-06 16:10 +0200
            Re: [PATCH 3/3] drm: Add CRTC_GET_SEQUENCE and CRTC_QUEUE_SEQUENCE ioctls Keith Packard <keithp@keithp.com> - 2017-07-06 18:30 +0200
              Re: [PATCH 3/3] drm: Add CRTC_GET_SEQUENCE and CRTC_QUEUE_SEQUENCE  ioctls Ville Syrjälä <ville.syrjala@linux.intel.com> - 2017-07-06 20:10 +0200
                Re: [PATCH 3/3] drm: Add CRTC_GET_SEQUENCE and CRTC_QUEUE_SEQUENCE ioctls Keith Packard <keithp@keithp.com> - 2017-07-06 20:30 +0200
                Re: [PATCH 3/3] drm: Add CRTC_GET_SEQUENCE and CRTC_QUEUE_SEQUENCE  ioctls Ville Syrjälä <ville.syrjala@linux.intel.com> - 2017-07-06 21:00 +0200
                Re: [PATCH 3/3] drm: Add CRTC_GET_SEQUENCE and CRTC_QUEUE_SEQUENCE ioctls Keith Packard <keithp@keithp.com> - 2017-07-06 21:50 +0200
      Re: [PATCH 3/3] drm: Add CRTC_GET_SEQUENCE and CRTC_QUEUE_SEQUENCE ioctls Keith Packard <keithp@keithp.com> - 2017-07-06 18:30 +0200
        Re: [PATCH 3/3] drm: Add CRTC_GET_SEQUENCE and CRTC_QUEUE_SEQUENCE ioctls Daniel Vetter <daniel@ffwll.ch> - 2017-07-06 23:50 +0200
  [PATCH 2/3] drm: Reorganize drm_pending_event to support future event types Keith Packard <keithp@keithp.com> - 2017-07-06 00:20 +0200
    Re: [PATCH 2/3] drm: Reorganize drm_pending_event to support future  event types Daniel Vetter <daniel@ffwll.ch> - 2017-07-06 09:40 +0200
      Re: [PATCH 2/3] drm: Reorganize drm_pending_event to support future event types Keith Packard <keithp@keithp.com> - 2017-07-06 17:40 +0200
        Re: [PATCH 2/3] drm: Reorganize drm_pending_event to support future  event types Daniel Vetter <daniel@ffwll.ch> - 2017-07-07 14:10 +0200

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