linux-kernel - Re: [PATCH v12 1/3] platform/chrome: cros_ec

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Date:   Mon, 26 Dec 2022 16:12:07 +0800
From:   Tzung-Bi Shih <tzungbi@...nel.org>
To:     Mark Hasemeyer <markhas@...omium.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Raul Rangel <rrangel@...omium.org>,
        Bhanu Prakash Maiya <bhanumaiya@...omium.org>,
        kernel test robot <lkp@...el.com>,
        Prashant Malani <pmalani@...omium.org>,
        Benson Leung <bleung@...omium.org>,
        Guenter Roeck <groeck@...omium.org>,
        chrome-platform@...ts.linux.dev
Subject: Re: [PATCH v12 1/3] platform/chrome: cros_ec_uart: Add cros-ec-uart
 transport layer

On Fri, Dec 09, 2022 at 09:26:22AM -0700, Mark Hasemeyer wrote:
> diff --git a/drivers/platform/chrome/cros_ec_uart.c b/drivers/platform/chrome/cros_ec_uart.c
[...]
> +static int cros_ec_uart_rx_bytes(struct serdev_device *serdev,
> +				 const u8 *data,
> +				 size_t count)
> +{
> +	struct ec_host_response *response;

There are 2 "response" in the context: struct response_info vs.
struct ec_host_response.  The pointer `response` here is only used for
setting `exp_len`.

I would suggest to introduce another pointer:
    struct response_info *resp = &ec_uart->response;
So that most of the following "ec_uart->response." could simplify to
"resp->".

[...]
> +	/* Read data_len if we received response header and if exp_len was not read before. */
> +	if (ec_uart->response.size >= sizeof(*response) &&
> +	    ec_uart->response.exp_len == 0) {
> +		response = (struct ec_host_response *) ec_uart->response.data;

Please drop the extra space.

> +static int cros_ec_uart_pkt_xfer(struct cros_ec_device *ec_dev,
> +				 struct cros_ec_command *ec_msg)
> +{
> +	struct cros_ec_uart *ec_uart = ec_dev->priv;
> +	struct serdev_device *serdev = ec_uart->serdev;
> +	struct ec_host_response *response;

Ditto, if using another pointer to struct response_info could simplify the
function a bit.

> +	unsigned int len;
> +	int ret, i;
> +	u8 sum = 0;

To make it clear, please drop the initialization and set it to 0 just right
before it is used.

[...]
> +	/* Validate checksum */
> +	for (i = 0; i < sizeof(*response) + response->data_len; i++)
> +		sum += ec_dev->din[i];

The function is long.  Setting sum to 0 before the loop improves the
readability.

> +static int cros_ec_uart_probe(struct serdev_device *serdev)
> +{
> +	struct device *dev = &serdev->dev;
> +	struct cros_ec_device *ec_dev;
> +	struct cros_ec_uart *ec_uart;
> +	int ret;
> +
> +	ec_uart = devm_kzalloc(dev, sizeof(*ec_uart), GFP_KERNEL);
> +	if (!ec_uart)
> +		return -ENOMEM;
> +
> +	ec_dev = devm_kzalloc(dev, sizeof(*ec_dev), GFP_KERNEL);
> +	if (!ec_dev)
> +		return -ENOMEM;
> +
> +	ec_uart->serdev = serdev;

The assignment can move somewhere before calling cros_ec_uart_acpi_probe().

> +
> +	ret = devm_serdev_device_open(dev, ec_uart->serdev);

Using `ec_uart->serdev` here makes less sense.  Please use `serdev` directly.