Re: [PATCH v3 2/2] drm/fb-helper: implement ioctl FBIO_WAITFORVSYNC

From	Michel Dänzer <michel@daenzer.net>
Newsgroups	linux.kernel
Subject	Re: [PATCH v3 2/2] drm/fb-helper: implement ioctl FBIO_WAITFORVSYNC
Date	2017-02-22 08:10 +0100
Message-ID	<tdzdL-6lr-5@gated-at.bofh.it> (permalink)
References	<tbatb-2fc-5@gated-at.bofh.it> <tbatb-2fc-3@gated-at.bofh.it> <tdfyp-161-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 21/02/17 07:00 PM, Stefan Lengfeld wrote:
> 
> 2/ Wait for a single vsync event on all active crtcs as Ville Syrjälä 
>    described here [2] in the optimal implementation.

FWIW, this seems like a bad idea, since with multiple active CRTCs it
would make it essentially random at which intervals the ioctl returns,
and which CRTCs are in vertical blank when it does. So it would be
useless for both timing and tearing prevention purposes, i.e. more or
less completely useless.

-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer

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[PATCH v3 2/2] drm/fb-helper: implement ioctl FBIO_WAITFORVSYNC Maxime Ripard <maxime.ripard@free-electrons.com> - 2017-02-15 17:20 +0100
  Re: [PATCH v3 2/2] drm/fb-helper: implement ioctl FBIO_WAITFORVSYNC Stefan Lengfeld <contact@stefanchrist.eu> - 2017-02-21 11:10 +0100
    Re: [PATCH v3 2/2] drm/fb-helper: implement ioctl FBIO_WAITFORVSYNC Ville Syrjälä <ville.syrjala@linux.intel.com> - 2017-02-21 12:00 +0100
      Re: [PATCH v3 2/2] drm/fb-helper: implement ioctl FBIO_WAITFORVSYNC Maxime Ripard <maxime.ripard@free-electrons.com> - 2017-02-23 02:00 +0100
        Re: [PATCH v3 2/2] drm/fb-helper: implement ioctl FBIO_WAITFORVSYNC Stefan Lengfeld <contact@stefanchrist.eu> - 2017-02-23 10:10 +0100
          Re: [PATCH v3 2/2] drm/fb-helper: implement ioctl FBIO_WAITFORVSYNC Daniel Vetter <daniel@ffwll.ch> - 2017-02-26 22:20 +0100
    Re: [PATCH v3 2/2] drm/fb-helper: implement ioctl FBIO_WAITFORVSYNC Michel Dänzer <michel@daenzer.net> - 2017-02-22 08:10 +0100

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