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Re: [PATCH v5 15/39] [media] v4l2: add a frame interval error event

From Pavel Machek <pavel@ucw.cz>
Newsgroups linux.kernel
Subject Re: [PATCH v5 15/39] [media] v4l2: add a frame interval error event
Date 2017-03-11 00:40 +0100
Message-ID <tjCiB-2B7-9@gated-at.bofh.it> (permalink)
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On Fri 2017-03-10 10:37:21, Steve Longerbeam wrote:
> Hi Hans,
> 
> On 03/10/2017 04:03 AM, Hans Verkuil wrote:
> >On 10/03/17 05:52, Steve Longerbeam wrote:
> >>Add a new FRAME_INTERVAL_ERROR event to signal that a video capture or
> >>output device has measured an interval between the reception or transmit
> >>completion of two consecutive frames of video that is outside the nominal
> >>frame interval by some tolerance value.
> >
> >Reading back what was said on this I agree with Sakari that this doesn't
> >belong here.
> >
> >Userspace can detect this just as easily (if not easier) with a timeout.
> >
> 
> 
> Unfortunately measuring frame intervals from userland is not accurate
> enough for i.MX6.
> 
> The issue here is that the IPUv3, specifically the CSI unit, can
> permanently lose vertical sync if there are truncated frames sent
> on the bt.656 bus. We have seen a single missing line of video cause
> loss of vertical sync. The only way to correct this is to shutdown
> the IPU capture hardware and restart, which can be accomplished
> simply by restarting streaming from userland.
> 
> There are no other indicators from the sensor about these short
> frame events (believe me, we've exhausted all avenues with the ADV718x).
> And the IPUv3 DMA engine has no status indicators for short frames
> either. So the only way to detect them is by measuring frame intervals.
> 
> The intervals have to be able to resolve a single line of missing video.
> With a PAL video source that requires better than 58 usec accuracy.
> 
> There is too much uncertainty to resolve this at user level. The
> driver is able to resolve this by measuring intervals between hardware
> interrupts as long as interrupt latency is reasonably low, and we
> have another method using the i.MX6 hardware input capture support
> that can measure these intervals very accurately with no errors
> introduced by interrupt latency.

Requiring < 58 usec interrupt latency for correct operation is a
little too optimistic, no?
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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[PATCH v5 00/39] i.MX Media Driver Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
  [PATCH v5 26/39] media: imx: Add VDIC subdev driver Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
  [PATCH v5 38/39] media: imx: csi: fix crop rectangle reset in sink set_fmt Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
  [PATCH v5 30/39] media: imx: add support for bayer formats Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
  [PATCH v5 35/39] media: imx: csi/fim: add support for frame intervals Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
  [PATCH v5 20/39] platform: add video-multiplexer subdevice driver Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
  [PATCH v5 29/39] ARM: imx_v6_v7_defconfig: Enable staging video4linux drivers Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
  [PATCH v5 09/39] ARM: dts: imx6-sabresd: add OV5642 and OV5640 camera sensors Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
  [PATCH v5 10/39] ARM: dts: imx6-sabreauto: create i2cmux for i2c3 Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
  [PATCH v5 08/39] ARM: dts: imx6-sabrelite: add OV5642 and OV5640 camera sensors Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
  [PATCH v5 01/39] [media] dt-bindings: Add bindings for video-multiplexer device Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
  [PATCH v5 24/39] media: imx: Add Capture Device Interface Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
  [PATCH v5 32/39] media: imx: csi: fix crop rectangle changes in set_fmt Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
  [PATCH v5 33/39] media: imx: mipi-csi2: enable setting and getting of frame rates Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
  [PATCH v5 25/39] media: imx: Add CSI subdev driver Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
  [PATCH v5 05/39] ARM: dts: imx6qdl: Add mipi_ipu1/2 multiplexers, mipi_csi, and their connections Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
  [PATCH v5 11/39] ARM: dts: imx6-sabreauto: add reset-gpios property for max7310_b Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
  [PATCH v5 21/39] UAPI: Add media UAPI Kbuild file Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
    Re: [PATCH v5 21/39] UAPI: Add media UAPI Kbuild file Sakari Ailus <sakari.ailus@iki.fi> - 2017-03-11 14:50 +0100
      Re: [PATCH v5 21/39] UAPI: Add media UAPI Kbuild file Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-11 19:30 +0100
        Re: [PATCH v5 21/39] UAPI: Add media UAPI Kbuild file Hans Verkuil <hverkuil@xs4all.nl> - 2017-03-13 11:00 +0100
  [PATCH v5 37/39] media: imx: csi: add frame skipping support Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
  [PATCH v5 22/39] media: Add userspace header file for i.MX Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
    Re: [PATCH v5 22/39] media: Add userspace header file for i.MX Hans Verkuil <hverkuil@xs4all.nl> - 2017-03-10 12:50 +0100
    Re: [PATCH v5 22/39] media: Add userspace header file for i.MX Pavel Machek <pavel@ucw.cz> - 2017-03-11 00:40 +0100
  [PATCH v5 36/39] media: imx: redo pixel format enumeration and negotiation Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
  [PATCH v5 15/39] [media] v4l2: add a frame interval error event Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
    Re: [PATCH v5 15/39] [media] v4l2: add a frame interval error event Hans Verkuil <hverkuil@xs4all.nl> - 2017-03-10 13:10 +0100
      Re: [PATCH v5 15/39] [media] v4l2: add a frame interval error event Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 19:40 +0100
        Re: [PATCH v5 15/39] [media] v4l2: add a frame interval error event Pavel Machek <pavel@ucw.cz> - 2017-03-11 00:40 +0100
          Re: [PATCH v5 15/39] [media] v4l2: add a frame interval error event Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-11 00:50 +0100
        Re: [PATCH v5 15/39] [media] v4l2: add a frame interval error event Hans Verkuil <hverkuil@xs4all.nl> - 2017-03-11 12:50 +0100
          Re: [PATCH v5 15/39] [media] v4l2: add a frame interval error event Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-11 19:20 +0100
            Re: [PATCH v5 15/39] [media] v4l2: add a frame interval error event Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-03-11 20:00 +0100
              Re: [PATCH v5 15/39] [media] v4l2: add a frame interval error event Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-11 20:00 +0100
              Re: [PATCH v5 15/39] [media] v4l2: add a frame interval error event Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-11 20:10 +0100
            Re: [PATCH v5 15/39] [media] v4l2: add a frame interval error event Hans Verkuil <hverkuil@xs4all.nl> - 2017-03-13 11:10 +0100
              Re: [PATCH v5 15/39] [media] v4l2: add a frame interval error event Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-03-13 11:50 +0100
                Re: [PATCH v5 15/39] [media] v4l2: add a frame interval error event Hans Verkuil <hverkuil@xs4all.nl> - 2017-03-13 12:00 +0100
                Re: [PATCH v5 15/39] [media] v4l2: add a frame interval error event Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-13 18:10 +0100
                Re: [PATCH v5 15/39] [media] v4l2: add a frame interval error event Hans Verkuil <hverkuil@xs4all.nl> - 2017-03-13 18:20 +0100
                Re: [PATCH v5 15/39] [media] v4l2: add a frame interval error event Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-13 22:50 +0100
  [PATCH v5 31/39] media: imx: csi: add support for bayer formats Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
  [PATCH v5 03/39] [media] dt/bindings: Add bindings for OV5640 Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:00 +0100
  [PATCH v5 14/39] add mux and video interface bridge entity functions Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:10 +0100
  [PATCH v5 07/39] ARM: dts: imx6qdl-sabrelite: remove erratum ERR006687 workaround Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:10 +0100
    Re: [PATCH v5 07/39] ARM: dts: imx6qdl-sabrelite: remove erratum  ERR006687 workaround Troy Kisky <troy.kisky@boundarydevices.com> - 2017-03-10 20:00 +0100
      Re: [PATCH v5 07/39] ARM: dts: imx6qdl-sabrelite: remove erratum  ERR006687 workaround Fabio Estevam <festevam@gmail.com> - 2017-03-10 20:20 +0100
        Re: [PATCH v5 07/39] ARM: dts: imx6qdl-sabrelite: remove erratum  ERR006687 workaround Pavel Machek <pavel@ucw.cz> - 2017-03-10 23:00 +0100
          Re: [PATCH v5 07/39] ARM: dts: imx6qdl-sabrelite: remove erratum  ERR006687 workaround Fabio Estevam <festevam@gmail.com> - 2017-03-10 23:10 +0100
  [PATCH v5 17/39] [media] v4l2-mc: add a function to inherit controls from a pipeline Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:10 +0100
    Re: [PATCH v5 17/39] [media] v4l2-mc: add a function to inherit  controls from a pipeline Hans Verkuil <hverkuil@xs4all.nl> - 2017-03-10 12:50 +0100
  [PATCH v5 12/39] ARM: dts: imx6-sabreauto: add pinctrl for gpt input capture Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:10 +0100
  [PATCH v5 18/39] [media] v4l: subdev: Add function to validate frame interval Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:10 +0100
    Re: [PATCH v5 18/39] [media] v4l: subdev: Add function to validate  frame interval Sakari Ailus <sakari.ailus@iki.fi> - 2017-03-11 14:50 +0100
      Re: [PATCH v5 18/39] [media] v4l: subdev: Add function to validate  frame interval Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-11 21:40 +0100
  [PATCH v5 04/39] ARM: dts: imx6qdl: Add compatible, clocks, irqs to MIPI CSI-2 node Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:10 +0100
  [PATCH v5 16/39] [media] v4l2: add a new-frame before end-of-frame event Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:10 +0100
    Re: [PATCH v5 16/39] [media] v4l2: add a new-frame before  end-of-frame event Hans Verkuil <hverkuil@xs4all.nl> - 2017-03-10 13:10 +0100
  [PATCH v5 06/39] ARM: dts: imx6qdl: add capture-subsystem device Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:10 +0100
  [PATCH v5 02/39] [media] dt-bindings: Add bindings for i.MX media driver Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-10 06:10 +0100
  Re: [PATCH v5 00/39] i.MX Media Driver Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-03-10 21:20 +0100
    Re: [PATCH v5 00/39] i.MX Media Driver Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-11 00:30 +0100
      Re: [PATCH v5 00/39] i.MX Media Driver Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-03-12 18:50 +0100
    Re: [PATCH v5 00/39] i.MX Media Driver Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-12 01:40 +0100
      Re: [PATCH v5 00/39] i.MX Media Driver Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-03-12 21:00 +0100
        Re: [PATCH v5 00/39] i.MX Media Driver Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-12 21:10 +0100
          Re: [PATCH v5 00/39] i.MX Media Driver Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-03-12 21:30 +0100
            Re: [PATCH v5 00/39] i.MX Media Driver Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-13 05:40 +0100
              Re: [PATCH v5 00/39] i.MX Media Driver Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-03-13 09:20 +0100
                Re: [PATCH v5 00/39] i.MX Media Driver Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-03-13 10:40 +0100
                Re: [PATCH v5 00/39] i.MX Media Driver Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-14 00:40 +0100
                Re: [PATCH v5 00/39] i.MX Media Driver Steve Longerbeam <steve_longerbeam@mentor.com> - 2017-03-14 00:40 +0100
  Re: [PATCH v5 00/39] i.MX Media Driver Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-03-12 19:00 +0100
    Re: [PATCH v5 00/39] i.MX Media Driver Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-12 20:30 +0100
      Re: [PATCH v5 00/39] i.MX Media Driver Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-03-12 20:40 +0100
        Re: [PATCH v5 00/39] i.MX Media Driver Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-12 20:50 +0100
          Re: [PATCH v5 00/39] i.MX Media Driver Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-12 21:20 +0100
            Re: [PATCH v5 00/39] i.MX Media Driver Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-12 21:40 +0100
              Re: [PATCH v5 00/39] i.MX Media Driver Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-12 21:40 +0100
              Re: [PATCH v5 00/39] i.MX Media Driver Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-03-12 21:50 +0100
                Re: [PATCH v5 00/39] i.MX Media Driver Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-03-12 22:20 +0100
  Re: [PATCH v5 00/39] i.MX Media Driver Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-03-12 20:50 +0100
    Re: [PATCH v5 00/39] i.MX Media Driver Steve Longerbeam <slongerbeam@gmail.com> - 2017-03-12 21:10 +0100
    Re: [PATCH v5 00/39] i.MX Media Driver Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-03-12 22:00 +0100
      Re: [PATCH v5 00/39] i.MX Media Driver Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-03-12 22:20 +0100
        Re: [PATCH v5 00/39] i.MX Media Driver Mauro Carvalho Chehab <mchehab@s-opensource.com> - 2017-03-12 23:20 +0100

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