Re: [PATCH v9 2/4] media: i2c: Add MAX9286 driver

From: Sakari Ailus
Date: Sat May 16 2020 - 17:51:36 EST


Hi Kieran,

Thanks for the update.

On Tue, May 12, 2020 at 04:51:03PM +0100, Kieran Bingham wrote:

...

> +static int max9286_enum_mbus_code(struct v4l2_subdev *sd,
> + struct v4l2_subdev_pad_config *cfg,
> + struct v4l2_subdev_mbus_code_enum *code)
> +{
> + if (code->pad || code->index > 0)
> + return -EINVAL;
> +
> + code->code = MEDIA_BUS_FMT_UYVY8_2X8;

Why UYVY8_2X8 and not UYVY8_1X16? In general, the single sample / pixel
variant of the format is generally used on the serial busses. This choice
was made when serial busses were introduced.

> +
> + return 0;
> +}
> +
> +static struct v4l2_mbus_framefmt *
> +max9286_get_pad_format(struct max9286_priv *priv,
> + struct v4l2_subdev_pad_config *cfg,
> + unsigned int pad, u32 which)
> +{
> + switch (which) {
> + case V4L2_SUBDEV_FORMAT_TRY:
> + return v4l2_subdev_get_try_format(&priv->sd, cfg, pad);
> + case V4L2_SUBDEV_FORMAT_ACTIVE:
> + return &priv->fmt[pad];
> + default:
> + return NULL;
> + }
> +}
> +
> +static int max9286_set_fmt(struct v4l2_subdev *sd,
> + struct v4l2_subdev_pad_config *cfg,
> + struct v4l2_subdev_format *format)
> +{
> + struct max9286_priv *priv = sd_to_max9286(sd);
> + struct v4l2_mbus_framefmt *cfg_fmt;
> +
> + if (format->pad >= MAX9286_SRC_PAD)
> + return -EINVAL;

You can remove these checks; it's been already done by the caller.

...

> +static int max9286_parse_dt(struct max9286_priv *priv)
> +{
> + struct device *dev = &priv->client->dev;
> + struct device_node *i2c_mux;
> + struct device_node *node = NULL;
> + unsigned int i2c_mux_mask = 0;
> +
> + of_node_get(dev->of_node);
> + i2c_mux = of_find_node_by_name(dev->of_node, "i2c-mux");
> + if (!i2c_mux) {
> + dev_err(dev, "Failed to find i2c-mux node\n");
> + of_node_put(dev->of_node);
> + return -EINVAL;
> + }
> +
> + /* Identify which i2c-mux channels are enabled */
> + for_each_child_of_node(i2c_mux, node) {
> + u32 id = 0;
> +
> + of_property_read_u32(node, "reg", &id);
> + if (id >= MAX9286_NUM_GMSL)
> + continue;
> +
> + if (!of_device_is_available(node)) {
> + dev_dbg(dev, "Skipping disabled I2C bus port %u\n", id);
> + continue;
> + }
> +
> + i2c_mux_mask |= BIT(id);
> + }
> + of_node_put(node);
> + of_node_put(i2c_mux);
> +
> + /* Parse the endpoints */
> + for_each_endpoint_of_node(dev->of_node, node) {
> + struct max9286_source *source;
> + struct of_endpoint ep;
> +
> + of_graph_parse_endpoint(node, &ep);
> + dev_dbg(dev, "Endpoint %pOF on port %d",
> + ep.local_node, ep.port);
> +
> + if (ep.port > MAX9286_NUM_GMSL) {
> + dev_err(dev, "Invalid endpoint %s on port %d",
> + of_node_full_name(ep.local_node), ep.port);
> + continue;
> + }
> +
> + /* For the source endpoint just parse the bus configuration. */
> + if (ep.port == MAX9286_SRC_PAD) {
> + struct v4l2_fwnode_endpoint vep = {
> + .bus_type = V4L2_MBUS_CSI2_DPHY
> + };
> + int ret;
> +
> + ret = v4l2_fwnode_endpoint_parse(
> + of_fwnode_handle(node), &vep);
> + if (ret) {
> + of_node_put(node);
> + of_node_put(dev->of_node);
> + return ret;
> + }
> +
> + if (vep.bus_type != V4L2_MBUS_CSI2_DPHY) {

This won't happen, the bus type will stay if you set it to a non-zero
value.

> + dev_err(dev,
> + "Media bus %u type not supported\n",
> + vep.bus_type);
> + v4l2_fwnode_endpoint_free(&vep);
> + of_node_put(node);
> + of_node_put(dev->of_node);
> + return -EINVAL;
> + }
> +
> + priv->csi2_data_lanes =
> + vep.bus.mipi_csi2.num_data_lanes;
> + v4l2_fwnode_endpoint_free(&vep);

No need to call this unless you use v4l2_fwnode_endpoint_alloc_parse().

And as you don't, you also won't know which frequencies are known to be
safe to use. That said, perhaps where this device is used having a random
frequency on that bus could not be an issue. Perhaps.

> +
> + continue;
> + }
> +
> + /* Skip if the corresponding GMSL link is unavailable. */
> + if (!(i2c_mux_mask & BIT(ep.port)))
> + continue;
> +
> + if (priv->sources[ep.port].fwnode) {
> + dev_err(dev,
> + "Multiple port endpoints are not supported: %d",
> + ep.port);
> +
> + continue;
> + }
> +
> + source = &priv->sources[ep.port];
> + source->fwnode = fwnode_graph_get_remote_endpoint(
> + of_fwnode_handle(node));
> + if (!source->fwnode) {
> + dev_err(dev,
> + "Endpoint %pOF has no remote endpoint connection\n",
> + ep.local_node);
> +
> + continue;
> + }
> +
> + priv->source_mask |= BIT(ep.port);
> + priv->nsources++;
> + }
> + of_node_put(node);
> + of_node_put(dev->of_node);
> +
> + priv->route_mask = priv->source_mask;
> +
> + return 0;
> +}

--
Kind regards,

Sakari Ailus