On Sun, 2017-02-19 at 23:02 +0100, Pavel Machek wrote:

Hi!

quoted

From: Philipp Zabel <p.zabel@pengutronix.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@pengutronix.de>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
--

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

quoted

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?

Yes. With the mmio bitfield muxes there can be more.

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

quoted

+struct vidsw {

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

This driver started as a two-input gpio controlled bus switch.
I changed the name when adding support for bitfield controlled
multiplexers with more than two inputs.

quoted

+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()...?

If neither field nor gpio are set, probe will have failed and this will
never be called.

quoted

+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?

We could change both to unsigned int, as both vidsw->num_pads and
endpoint.base.port are unsigned int, and they are only compared/assigned
to those and each other.

quoted

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

     I. 

quoted

+	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?

To support CSI-2 multiplexers, yes.

quoted

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

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

Thanks,
								Pavel

regards
Philipp