Re: [PATCH v6 7/8] media: i2c: add DS90UB913 driver

[Tomi Valkeinen]

On 09/01/2023 13:07, Andy Shevchenko wrote:
> On Sun, Jan 08, 2023 at 06:06:34AM +0200, Laurent Pinchart wrote:
> > On Thu, Jan 05, 2023 at 04:03:06PM +0200, Tomi Valkeinen wrote:
>
> ...
>
> > > +	scnprintf(priv->gpio_chip_name, sizeof(priv->gpio_chip_name), "%s",
> > > +		  dev_name(dev));
> >
> > I think you can use strscpy().
>
> Actually I'm not sure we even need that variable. What is the lifetime of
> the dev and gc? I believe they are the same or gc's one is shorter, hence
> dev_name() can be used directly, no?

I think this is a valid point, no need for the extra variable afaics.

> ...
>
> > > +	gc->of_node = priv->client->dev.of_node;
>
> We don't have of_node anymore in gc. And if the parent device is set, you can
> drop this line (it will work with older and newer kernels. Otherwise, use
> fwnode.

What do you mean "we don't have of_node anymore"?

> ...
>
> > > +	ret = gpiochip_add_data(gc, priv);
> > > +	if (ret) {
> > > +		dev_err(dev, "Failed to add GPIOs: %d\n", ret);
>
> > > +		return ret;
> > > +	}
> > > +
> > > +	return 0;
>
> return ret;

I'm not a fan of that style. I like my error handling ifs to return the 
error inside the if block, and a successful function ends in a "return 0".

> ...
>
> > > +	ep_node = of_graph_get_endpoint_by_regs(dev->of_node, 0, 0);
>
> Why this can't be fwnode_handle from day 1?

I guess it can. It's an old driver and there has been no need to convert 
to fwnode, so we're still using OF.

> > > +	if (!ep_node) {
> > > +		dev_err(dev, "No graph endpoint\n");
> > > +		return -ENODEV;
> > > +	}
>
> ...
>
> > > +	ep_np = of_graph_get_endpoint_by_regs(np, 0, 0);
> > > +	if (!ep_np) {
> > > +		dev_err(dev, "OF: no endpoint\n");
> > > +		return -ENOENT;
> > > +	}
>
> Ditto.
>
> > > +	ret = of_property_read_u32(ep_np, "pclk-sample", &priv->pclk_polarity);
> > > +
> > > +	of_node_put(ep_np);
>
> Ditto.
>
> ...
>
> > > +		return ret;
> > > +	}
> > > +
> > > +	return 0;
>
> return ret;
>
> ...
>
> > > +	priv->plat_data = dev_get_platdata(&client->dev);
> > > +	if (!priv->plat_data) {
> > > +		dev_err(dev, "Platform data missing\n");
> > > +		return -ENODEV;
>
> 	return dev_err_probe(...); ?

Isn't the idea with dev_err_probe to use it where -EPROBE_DEFER might be 
the error? That's not the case here.

Buuut reading the relevant docs a bit more shows that it's actually 
recommended to be used in this kind of cases too, so you're right.

> > > +	}
>
> ...
>
> > > +	priv->regmap = devm_regmap_init_i2c(client, &ub913_regmap_config);
> > > +	if (IS_ERR(priv->regmap)) {
> > > +		dev_err(dev, "Failed to init regmap\n");
> > > +		return PTR_ERR(priv->regmap);
>
> Ditto?
>
> > > +	}
>
> ...
>
> > > +#ifdef CONFIG_OF
> >
> > The driver depends on CONFIG_OF so I would drop this, as well as the
> > of_match_ptr().
>
> Even if there is no OF dependency, these ugly ifdeffery with of_match_ptr()
> are error prone (compilation wise).
>
> ...
>
> > > +static const struct of_device_id ub913_dt_ids[] = {
> > > +	{ .compatible = "ti,ds90ub913a-q1", },
>
> Inner comma is not needed.

Ok.

> > > +	{}
> > > +};
>
> ...
>
> > > +static struct i2c_driver ds90ub913_driver = {
> > > +	.probe_new	= ub913_probe,
> > > +	.remove		= ub913_remove,
> > > +	.id_table	= ub913_id,
> > > +	.driver = {
> > > +		.name	= "ds90ub913a",
>
> > > +		.owner = THIS_MODULE,
>
> This is something like for 5+ years is not needed, as the below macro sets it
> for you.

Ok.

> > > +		.of_match_table = of_match_ptr(ub913_dt_ids),
> > > +	},
> > > +};
>
> > > +
>
> Redundant blank line.
>
> > > +module_i2c_driver(ds90ub913_driver);

 Tomi