linux-kernel - Re: [PATCH v3 2/2] usb: typec: ucsi: Implement ChromeOS UCSI driver

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Date: Mon, 8 Apr 2024 16:13:29 +0800
From: Tzung-Bi Shih <tzungbi@...nel.org>
To: Pavan Holla <pholla@...omium.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Heikki Krogerus <heikki.krogerus@...ux.intel.com>,
	Benson Leung <bleung@...omium.org>,
	Guenter Roeck <groeck@...omium.org>, linux-kernel@...r.kernel.org,
	linux-usb@...r.kernel.org,
	Abhishek Pandit-Subedi <abhishekpandit@...omium.org>,
	chrome-platform@...ts.linux.dev
Subject: Re: [PATCH v3 2/2] usb: typec: ucsi: Implement ChromeOS UCSI driver

On Wed, Apr 03, 2024 at 06:05:22PM +0000, Pavan Holla wrote:
> Implementation of a UCSI transport driver for ChromeOS.
> This driver will be loaded if the ChromeOS EC implements a PPM.

How this driver get probed?  From drivers/mfd/cros_ec_dev.c?  If so, there is
no "cros-ec-ucsi" in the MFD driver yet.

> diff --git a/drivers/usb/typec/ucsi/cros_ec_ucsi.c b/drivers/usb/typec/ucsi/cros_ec_ucsi.c
> [...]
> +static int cros_ucsi_async_write(struct ucsi *ucsi, unsigned int offset,
> +				 const void *val, size_t val_len)
> +{
> +	struct cros_ucsi_data *udata = ucsi_get_drvdata(ucsi);
> +	uint8_t ec_buffer[MAX_EC_DATA_SIZE + sizeof(struct ec_params_ucsi_ppm_set)];
> +	struct ec_params_ucsi_ppm_set *req = (struct ec_params_ucsi_ppm_set *)ec_buffer;
> +	int ret = 0;

The initialization is redundant.  `ret` will be overridden soon.

> +	if (val_len > MAX_EC_DATA_SIZE) {
> +		dev_err(udata->dev, "Can't write %zu bytes. Too big.", val_len);
> +		return -EINVAL;
> +	}
> +
> +	memset(req, 0, sizeof(ec_buffer));

The `memset` is redundant.

> +	req->offset = offset;
> +	memcpy(req->data, val, val_len);
> +	ret = cros_ec_cmd(udata->ec, 0, EC_CMD_UCSI_PPM_SET,
> +			  req, sizeof(struct ec_params_ucsi_ppm_set) + val_len, NULL, 0);

`sizeof(*req)`.

> +static int cros_ucsi_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> [...]
> +	udata->ucsi = ucsi_create(udata->dev, &cros_ucsi_ops);

`dev`.

> [...]
> +static const struct platform_device_id cros_ec_ucsi_id[] = {

To be consistent with other symbols, consider either:
- s/cros_ec_/cros_/ for the symbol.
or
- s/cros_ucsi_/cros_ec_ucsi_/g for echoing the file name.

> +	{ "cros-ec-ucsi"},

The driver has declared DRV_NAME, use it.  `{ DRV_NAME, 0 },`.

> +	{}
> +};
> +MODULE_DEVICE_TABLE(platform, cros_ec_ucsi_id);

Ditto.

> +static struct platform_driver cros_ucsi_driver = {
> +	.driver = {
> +		.name = DRV_NAME,
> +		.pm = &cros_ucsi_pm_ops,
> +	},
> +	.id_table = cros_ec_ucsi_id,

Ditto.