linux-kernel - Re: [PATCH 3/3] hwmon: (nct6775) Support access via Asus WMI (v2)

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Date:   Thu, 9 Sep 2021 20:01:36 +0300
From:   Andy Shevchenko <andriy.shevchenko@...el.com>
To:     Denis Pauk <pauk.denis@...il.com>
Cc:     Bernhard Seibold <mail@...nhard-seibold.de>,
        Pär Ekholm <pehlm@...holm.org>,
        to.eivind@...il.com, "Artem S . Tashkinov" <aros@....com>,
        Vittorio Roberto Alfieri <me@...toor.com>,
        Guenter Roeck <linux@...ck-us.net>,
        Jean Delvare <jdelvare@...e.com>, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] hwmon: (nct6775) Support access via Asus WMI (v2)

On Thu, Sep 09, 2021 at 12:36:04AM +0300, Denis Pauk wrote:
> Support accessing the NCT677x via Asus WMI functions.
> 
> On mainboards that support this way of accessing the chip,
> the driver will usually not work without this option since
> in these mainboards, ACPI will mark the I/O port as used.

...

> +static int asuswmi_evaluate_method(u32 method_id,
> +		u8 bank, u8 reg, u8 val, u32 *retval)

Indentation can be better.
Ditto for many lines in this change.

> +{
> +	u32 args = bank | (reg << 8) | (val << 16);
> +	struct acpi_buffer input = { (acpi_size) sizeof(args), &args };
> +	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
> +	acpi_status status;
> +	union acpi_object *obj;
> +	u32 tmp = 0;
> +
> +	status = wmi_evaluate_method(ASUSWMI_MGMT2_GUID, 0, method_id,
> +				     &input, &output);
> +
> +	if (ACPI_FAILURE(status))
> +		return -EIO;

> +	obj = (union acpi_object *)output.pointer;

Do you need casting?

> +	if (obj && obj->type == ACPI_TYPE_INTEGER)
> +		tmp = (u32) obj->integer.value;

Ditto.

> +	if (retval)
> +		*retval = tmp;
> +
> +	kfree(obj);
> +
> +	if (tmp == ASUSWMI_UNSUPPORTED_METHOD)
> +		return -ENODEV;
> +	return 0;
> +}

...

> +static inline int
> +nct6775_asuswmi_read(u8 bank, u8 reg, u8 *val)

One line.

> +{
> +	u32 tmp;
> +	int ret = asuswmi_evaluate_method(ASUSWMI_METHODID_RHWM, bank, reg, 0, &tmp);

> +	*val = tmp & 0xff;

Do you need  ' & 0xff' part?

> +	return ret;
> +}

...

> +	if (data->access == access_asuswmi) {
> +		data->bank = bank;
> +		return;
> +	}

It means you have to introduce a new callback ->set_bank() (in a separate change).

...

> +	if (data->access == access_asuswmi) {
> +		nct6775_asuswmi_read(data->bank, reg, &tmp);
> +		res = (tmp & 0xff);
> +		if (word_sized) {
> +			nct6775_asuswmi_read(data->bank,
> +					(reg & 0xff) + 1, &tmp);
> +			res = (res << 8) + (tmp & 0xff);
> +		}
> +		return res;
> +	}

Similar.

...

> +	if (data->access == access_asuswmi) {
> +		if (word_sized) {
> +			nct6775_asuswmi_write(data->bank, (reg & 0xff),
> +					(value >> 8) & 0xff);
> +			nct6775_asuswmi_write(data->bank, (reg & 0xff) + 1,
> +					value & 0xff);
> +		} else {
> +			nct6775_asuswmi_write(data->bank, (reg & 0xff),
> +					value);
> +		}
> +
> +		return 0;
> +	}

Similar.

...

> +	if (sio_data->access == access_direct) {
> +		res = platform_get_resource(pdev, IORESOURCE_IO, 0);
> +		if (!res)
> +			return -EBUSY;
>  
> -	if (!devm_request_region(&pdev->dev, res->start, IOREGION_LENGTH,
> -				 DRVNAME))
> -		return -EBUSY;
> +		if (!devm_request_region(&pdev->dev, res->start, IOREGION_LENGTH,
> +					 DRVNAME))
> +			return -EBUSY;
> +	}

Maybe it should be part of some kind of ->setup()?

...

> +static const char * const asus_wmi_boards[] = {
> +	"PRIME B460-PLUS",
> +	"ROG CROSSHAIR VIII IMPACT",
> +	"ROG STRIX B550-E GAMING",
> +	"ROG STRIX B550-F GAMING (WI-FI)",
> +	"ROG STRIX Z490-I GAMING",
> +	"TUF GAMING B550M-PLUS",
> +	"TUF GAMING B550M-PLUS (WI-FI)",
> +	"TUF GAMING B550-PLUS",
> +	"TUF GAMING X570-PLUS",

> +	"TUF GAMING X570-PRO (WI-FI)"

+ comma at the end.

> +};

...

> +		if (match_string(asus_wmi_boards,
> +				ARRAY_SIZE(asus_wmi_boards), board_name) != -EINVAL) {

	err = match_string(...);
	if (err < 0) {
		...
	}

> +			/* if reading chip id via WMI succeeds, use WMI */
> +			if (!nct6775_asuswmi_read(0, NCT6775_REG_CHIPID, &tmp)) {
> +				pr_info("Using Asus WMI to access chip\n");
> +				access = access_asuswmi;
> +			}
> +		}

-- 
With Best Regards,
Andy Shevchenko