linux-kernel - Re: [PATCH v4 15/36] platform: add video-multiplexer subdevice driver

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Message-ID: <20170219220237.GD32327@amd>
Date:   Sun, 19 Feb 2017 23:02:37 +0100
From:   Pavel Machek <pavel@....cz>
To:     Steve Longerbeam <slongerbeam@...il.com>
Cc:     robh+dt@...nel.org, mark.rutland@....com, shawnguo@...nel.org,
        kernel@...gutronix.de, fabio.estevam@....com,
        linux@...linux.org.uk, mchehab@...nel.org, hverkuil@...all.nl,
        nick@...anahar.org, markus.heiser@...marIT.de,
        p.zabel@...gutronix.de, laurent.pinchart+renesas@...asonboard.com,
        bparrot@...com, geert@...ux-m68k.org, arnd@...db.de,
        sudipm.mukherjee@...il.com, minghsiu.tsai@...iatek.com,
        tiffany.lin@...iatek.com, jean-christophe.trotin@...com,
        horms+renesas@...ge.net.au, niklas.soderlund+renesas@...natech.se,
        robert.jarzmik@...e.fr, songjun.wu@...rochip.com,
        andrew-ct.chen@...iatek.com, gregkh@...uxfoundation.org,
        shuah@...nel.org, sakari.ailus@...ux.intel.com,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-media@...r.kernel.org,
        devel@...verdev.osuosl.org, Sascha Hauer <s.hauer@...gutronix.de>,
        Steve Longerbeam <steve_longerbeam@...tor.com>
Subject: Re: [PATCH v4 15/36] platform: add video-multiplexer subdevice driver

Hi!

> From: Philipp Zabel <p.zabel@...gutronix.de>
> 
> This driver can handle SoC internal and external video bus multiplexers,
> controlled either by register bit fields or by a GPIO. The subdevice
> passes through frame interval and mbus configuration of the active input
> to the output side.
> 
> Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
> Signed-off-by: Philipp Zabel <p.zabel@...gutronix.de>
> --
>

Again, this is slightly non-standard format. Normally changes from v1
go below ---, but in your case it would cut off the signoff...

> diff --git a/Documentation/devicetree/bindings/media/video-multiplexer.txt b/Documentation/devicetree/bindings/media/video-multiplexer.txt
> new file mode 100644
> index 0000000..9d133d9
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/media/video-multiplexer.txt
> @@ -0,0 +1,59 @@
> +Video Multiplexer
> +=================
> +
> +Video multiplexers allow to select between multiple input ports. Video received
> +on the active input port is passed through to the output port. Muxes described
> +by this binding may be controlled by a syscon register bitfield or by a GPIO.
> +
> +Required properties:
> +- compatible : should be "video-multiplexer"
> +- reg: should be register base of the register containing the control bitfield
> +- bit-mask: bitmask of the control bitfield in the control register
> +- bit-shift: bit offset of the control bitfield in the control register
> +- gpios: alternatively to reg, bit-mask, and bit-shift, a single GPIO phandle
> +  may be given to switch between two inputs
> +- #address-cells: should be <1>
> +- #size-cells: should be <0>
> +- port@*: at least three port nodes containing endpoints connecting to the
> +  source and sink devices according to of_graph bindings. The last port is
> +  the output port, all others are inputs.

At least three? I guess it is exactly three with the gpio?

Plus you might want to describe which port correspond to which gpio
state/bitfield values...

> +struct vidsw {

I knew it: it is secretely a switch! :-).

> +static void vidsw_set_active(struct vidsw *vidsw, int active)
> +{
> +	vidsw->active = active;
> +	if (active < 0)
> +		return;
> +
> +	dev_dbg(vidsw->subdev.dev, "setting %d active\n", active);
> +
> +	if (vidsw->field)
> +		regmap_field_write(vidsw->field, active);
> +	else if (vidsw->gpio)
> +		gpiod_set_value(vidsw->gpio, active);

         else dev_err()...?
	 
> +static int vidsw_async_init(struct vidsw *vidsw, struct device_node *node)
> +{
> +	struct device_node *ep;
> +	u32 portno;
> +	int numports;

numbports is int, so I guess portno should be, too?

> +		portno = endpoint.base.port;
> +		if (portno >= numports - 1)
> +			continue;


> +	if (!pad) {
> +		/* Mirror the input side on the output side */
> +		cfg->type = vidsw->endpoint[vidsw->active].bus_type;
> +		if (cfg->type == V4L2_MBUS_PARALLEL ||
> +		    cfg->type == V4L2_MBUS_BT656)
> +			cfg->flags = vidsw->endpoint[vidsw->active].bus.parallel.flags;
> +	}

Will this need support for other V4L2_MBUS_ values?

> +MODULE_AUTHOR("Sascha Hauer, Pengutronix");
> +MODULE_AUTHOR("Philipp Zabel, Pengutronix");

Normally, MODULE_AUTHOR contains comma separated names of authors,
perhaps with <email@...resses>. Not sure two MODULE_AUTHORs per file
will work.

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

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