Hi Pavel,

On Mon, Feb 13, 2017 at 10:54:20AM +0100, Pavel Machek wrote:

Hi!

quoted

quoted

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.

Light switches are mostly on/off switches. It'd be interesting to have a
light switch that you could use to light either of the light bulbs in a room
but not to switch both of them on at the same time. Or off... :-)

I wonder if everyone would be happy with a statement saying that it's a
on / on switch which is used to implement a multiplexer?

quoted

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.

It's here, slightly hidden in plain sight in the same patch with the MUX
framework:

<URL:https://www.mail-archive.com/linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org/msg1328763.html>

quoted

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?

I don't think there's one. But with MUX API, we'll be fine using a single
driver instead of two (other one for syscon on iMX).

Cc Steve and Philipp.

-- 
Kind regards,

Sakari Ailus
e-mail: sakari.ailus-X3B1VOXEql0@public.gmane.org	XMPP: sailus-PCDdDYkjdNMDXYZnReoRVg@public.gmane.org
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