linux-kernel - Re: [PATCH] devicetree: Add video bus switch

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Message-ID: <20170208213609.lnemfbzitee5iur2@rob-hp-laptop>
Date:   Wed, 8 Feb 2017 15:36:09 -0600
From:   Rob Herring <robh@...nel.org>
To:     Pavel Machek <pavel@....cz>
Cc:     Sakari Ailus <sakari.ailus@....fi>, devicetree@...r.kernel.org,
        ivo.g.dimitrov.75@...il.com, sre@...nel.org, pali.rohar@...il.com,
        linux-media@...r.kernel.org, galak@...eaurora.org,
        mchehab@....samsung.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] devicetree: Add video bus switch

On Fri, Feb 03, 2017 at 01:35:08PM +0100, Pavel Machek wrote:
> 
> N900 contains front and back camera, with a switch between the
> two. This adds support for the switch component, and it is now
> possible to select between front and back cameras during runtime.
> 
> This adds documentation for the devicetree binding.
> 
> Signed-off-by: Sebastian Reichel <sre@...nel.org>
> Signed-off-by: Ivaylo Dimitrov <ivo.g.dimitrov.75@...il.com>
> Signed-off-by: Pavel Machek <pavel@....cz>
> 
> 
> diff --git a/Documentation/devicetree/bindings/media/video-bus-switch.txt b/Documentation/devicetree/bindings/media/video-bus-switch.txt
> new file mode 100644
> index 0000000..1b9f8e0
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/video-bus-switch.txt
> @@ -0,0 +1,63 @@
> +Video Bus Switch Binding
> +========================

I'd call it a mux rather than switch.

BTW, there's a new mux-controller binding under review you might look 
at. It would only be needed here if the mux ctrl also controls other 
things.

> +
> +This is a binding for a gpio controlled switch for camera interfaces. Such a
> +device is used on some embedded devices to connect two cameras to the same
> +interface of a image signal processor.
> +
> +Required properties
> +===================
> +
> +compatible	: must contain "video-bus-switch"

video-bus-gpio-mux

> +switch-gpios	: GPIO specifier for the gpio, which can toggle the

mux-gpios to align with existing GPIO controlled muxes.

> +		  selected camera. The GPIO should be configured, so
> +		  that a disabled GPIO means, that the first port is
> +		  selected.
> +
> +Required Port nodes
> +===================
> +
> +More documentation on these bindings is available in
> +video-interfaces.txt in the same directory.
> +
> +reg		: The interface:
> +		  0 - port for image signal processor
> +		  1 - port for first camera sensor
> +		  2 - port for second camera sensor

This could be used for display side as well. So describe these just as 
inputs and outputs.

Rob