Re: [PATCH 16/16] drivers/fsi: Add GPIO based FSI master

From: Jeremy Kerr
Date: Thu Dec 08 2016 - 23:12:14 EST


Hi Chris,

> +static ssize_t store_scan(struct device *dev,
> + struct device_attribute *attr,
> + const char *buf,
> + size_t count)
> +{
> + struct fsi_master_gpio *master = dev_get_drvdata(dev);
> +
> + fsi_master_gpio_init(master);
> +
> + /* clear out any old scan data if present */
> + fsi_master_unregister(&master->master);
> + fsi_master_register(&master->master);
> +
> + return count;
> +}
> +
> +static DEVICE_ATTR(scan, 0200, NULL, store_scan);

I think it would make more sense to have the scan attribute populated by
the fsi core; we want this on all masters, not just GPIO.

Currently, the only GPIO-master-specific functionality here is the
fsi_master_gpio_init() - but isn't this something that we can do at
probe time instead?

> +static int fsi_master_gpio_probe(struct platform_device *pdev)
> +{
> + struct fsi_master_gpio *master;
> + struct gpio_desc *gpio;
> +
> + master = devm_kzalloc(&pdev->dev, sizeof(*master), GFP_KERNEL);
> + if (!master)
> + return -ENOMEM;

We should be populating master->dev.parent, see

https://github.com/jk-ozlabs/linux/commit/5225d6c47


> + /* Optional pins */
> +
> + gpio = devm_gpiod_get(&pdev->dev, "trans", 0);
> + if (IS_ERR(gpio))
> + dev_dbg(&pdev->dev, "probe: failed to get trans pin\n");
> + else
> + master->gpio_trans = gpio;

I found devm_gpiod_get_optional(), which might make this a little
neater.

Cheers,


Jeremy