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Re: [PATCH] devicetree: Add video bus switch

From Pavel Machek <pavel@ucw.cz>
Newsgroups linux.kernel
Subject Re: [PATCH] devicetree: Add video bus switch
Date 2017-02-13 11:00 +0100
Message-ID <talAn-1ZB-37@gated-at.bofh.it> (permalink)
References (5 earlier) <t8J45-6aF-1@gated-at.bofh.it> <t96am-42G-7@gated-at.bofh.it> <t96al-42G-5@gated-at.bofh.it> <t9pwm-7Pl-5@gated-at.bofh.it> <t9rHQ-U6-17@gated-at.bofh.it>
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Hi!

> > Take a look at the wikipedia. If you do "one at a time" at 100Hz, you
> > can claim it is time-domain multiplex. But we are plain switching the
> > cameras. It takes second (or so) to setup the pipeline.
> > 
> > This is not multiplex.
> 
> The functionality is still the same, isn't it? Does it change what it is if
> the frequency might be 100 Hz or 0,01 Hz?

Well. In your living your you can have a switch, which is switch at
much less than 0.01Hz. You can also have a dimmer, which is a PWM,
which is switch at 100Hz or so. So yes, I'd say switch and mux are
different things.

> I was a bit annoyed for having to have two drivers for switching the source
> (one for GPIO, another for syscon / register), where both of the drivers
> would be essentially the same with the minor exception of having a slightly
> different means to toggle the mux setting.

Well, most of the video-bus-switch is the video4linux glue. Actual
switching is very very small part. So.. where is the other driver?
Looks like we have the same problem.

> The MUX framework adds an API for controlling the MUX. Thus we'll need only
> a single driver that uses the MUX framework API for V4L2. As an added bonus,
> V4L2 would be in line with the rest of the MUX usage in the kernel.
> 
> The set appears to already contain a GPIO MUX. What's needed would be to use
> the MUX API instead of direct GPIOs usage.

If there's a driver that already does switching for video4linux
devices? Do you have a pointer?

								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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Thread

[PATCH] devicetree: Add video bus switch Pavel Machek <pavel@ucw.cz> - 2017-02-03 13:40 +0100
  Re: [PATCH] devicetree: Add video bus switch Sakari Ailus <sakari.ailus@iki.fi> - 2017-02-03 14:10 +0100
    Re: [PATCH] devicetree: Add video bus switch Pavel Machek <pavel@ucw.cz> - 2017-02-03 22:10 +0100
      Re: [PATCH] devicetree: Add video bus switch Sakari Ailus <sakari.ailus@iki.fi> - 2017-02-03 22:40 +0100
        Re: [PATCH] devicetree: Add video bus switch Pavel Machek <pavel@ucw.cz> - 2017-02-04 23:00 +0100
          Re: [PATCH] devicetree: Add video bus switch Sakari Ailus <sakari.ailus@iki.fi> - 2017-02-04 23:40 +0100
            Re: [PATCH] devicetree: Add video bus switch Pavel Machek <pavel@ucw.cz> - 2017-02-05 22:20 +0100
              Re: [PATCH] devicetree: Add video bus switch Sebastian Reichel <sre@kernel.org> - 2017-02-06 00:50 +0100
                [PATCH] media: add operation to get configuration of "the other  side" of the link Pavel Machek <pavel@ucw.cz> - 2017-02-06 10:40 +0100
  Re: [PATCH] devicetree: Add video bus switch Pali Rohár <pali.rohar@gmail.com> - 2017-02-03 14:40 +0100
    Re: [PATCH] devicetree: Add video bus switch Pavel Machek <pavel@ucw.cz> - 2017-02-03 22:10 +0100
      Re: [PATCH] devicetree: Add video bus switch Sebastian Reichel <sre@kernel.org> - 2017-02-04 02:10 +0100
  Re: [PATCH] devicetree: Add video bus switch Rob Herring <robh@kernel.org> - 2017-02-08 23:20 +0100
    Re: [PATCH] devicetree: Add video bus switch Pavel Machek <pavel@ucw.cz> - 2017-02-08 23:40 +0100
      Re: [PATCH] devicetree: Add video bus switch Rob Herring <robh@kernel.org> - 2017-02-10 00:20 +0100
        Re: [PATCH] devicetree: Add video bus switch Pavel Machek <pavel@ucw.cz> - 2017-02-10 21:00 +0100
          Re: [PATCH] devicetree: Add video bus switch Sakari Ailus <sakari.ailus@iki.fi> - 2017-02-10 23:20 +0100
            Re: [PATCH] devicetree: Add video bus switch Pavel Machek <pavel@ucw.cz> - 2017-02-13 11:00 +0100
              Re: [PATCH] devicetree: Add video bus switch Sakari Ailus <sakari.ailus@iki.fi> - 2017-02-13 11:30 +0100
      Re: [PATCH] devicetree: Add video bus switch Rob Herring <robh@kernel.org> - 2017-02-10 00:20 +0100
    Re: [PATCH] devicetree: Add video bus switch Pavel Machek <pavel@ucw.cz> - 2017-02-09 00:00 +0100
      Re: [PATCH] devicetree: Add video bus switch Rob Herring <robh@kernel.org> - 2017-02-10 00:20 +0100
        Re: [PATCH] devicetree: Add video bus switch Pavel Machek <pavel@ucw.cz> - 2017-02-10 22:20 +0100

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