linux-kernel - Re: [PATCH v2] platform/x86: add Gigabyte WMI temperature driver

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Date:   Thu, 8 Apr 2021 16:39:47 +0200
From:   Thomas Weißschuh <linux@...ssschuh.net>
To:     Barnabás Pőcze <pobrn@...tonmail.com>
Cc:     "platform-driver-x86@...r.kernel.org" 
        <platform-driver-x86@...r.kernel.org>,
        Mark Gross <mgross@...ux.intel.com>,
        Hans de Goede <hdegoede@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Matthew Garrett <mjg59@...f.ucam.org>
Subject: Re: [PATCH v2] platform/x86: add Gigabyte WMI temperature driver

Hi,

On Mi, 2021-04-07T18:27+0000, Barnabás Pőcze wrote:
> 2021. április 5., hétfő 22:48 keltezéssel, Thomas Weißschuh írta:
> > Tested with a X570 I Aorus Pro Wifi.
> > The mainboard contains an ITE IT8688E chip for management.
> > This chips is also handled by drivers/hwmon/i87.c but as it is also used
> > by the firmware itself it needs an ACPI driver.
> 
> I gather this means you're getting the
> 
>   ACPI Warning: SystemIO range ... conflicts with ...
>   ACPI: If an ACPI driver is available for this device, you should use it instead of the native driver
> 
> warning?

Exactly.

> > +struct gigabyte_wmi_args {
> > +	u32 arg1;
> > +};
> > +
> > +static int gigabyte_wmi_perform_query(enum gigabyte_wmi_commandtype command,
> > +		struct gigabyte_wmi_args *args, struct acpi_buffer *out)
> > +{
> > +	const struct acpi_buffer in = {
> > +		.length = sizeof(*args),
> > +		.pointer = args,
> > +	};
> > +
> > +	acpi_status ret = wmi_evaluate_method(GIGABYTE_WMI_GUID, 0x0, command, &in, out);
> 
> Ideally, you'd use the WMI device that was passed to the probe method to do the query
> using `wmidev_evaluate_method()`. You can pass the WMI device pointer
> to `devm_hwmon_device_register_with_info()` in the `drvdata` argument,
> then in the ->read() callback you can retrieve it:
> 
>   static int gigabyte_wmi_hwmon_read(struct device *dev, ...)
>   {
>     struct wmi_device *wdev = dev_get_drvdata(dev);
> 
> and then you can pass that to the other functions.

Done.

> > +	if (ret == AE_OK) {
> > +		return 0;
> > +	} else {
> > +		return -EIO;
> > +	};
> 
> The `;` is not needed. And please use `ACPI_FAILURE()` or `ACPI_SUCCESS()`
> to check the returned value. For example:
> 
>   acpi_status ret = ...;
>   if (ACPI_FAILURE(ret))
>     return -EIO;
> 
>   return 0;

Done.

> > +}
> > +
> > +static int gigabyte_wmi_query_integer(enum gigabyte_wmi_commandtype command,
> > +		struct gigabyte_wmi_args *args, u64 *res)
> > +{
> > +	union acpi_object *obj;
> > +	struct acpi_buffer result = { ACPI_ALLOCATE_BUFFER, NULL };
> > +	int ret;
> > +
> > +	ret = gigabyte_wmi_perform_query(command, args, &result);
> > +	if (ret) {
> > +		goto out;
> 
> I believe if this branch is taken, no buffer is allocated (due to the failure),
> so you can just `return ret;` here and do away with the goto completely - if I'm not mistaken.

Done.

> > +static const struct hwmon_channel_info *gigabyte_wmi_hwmon_info[] = {
> > +	HWMON_CHANNEL_INFO(temp,
> > +			HWMON_T_INPUT,
> > +			HWMON_T_INPUT,
> > +			HWMON_T_INPUT,
> > +			HWMON_T_INPUT,
> > +			HWMON_T_INPUT,
> > +			HWMON_T_INPUT),
> > +	NULL,
>             ^
> Minor thing: usually commas after sentinel values are omitted.

Done.

> > +static const struct wmi_device_id gigabyte_wmi_id_table[] = {
> > +	{ GIGABYTE_WMI_GUID, NULL },
> > +	{ },
>            ^
> Same here.

Done.

> 
> > +};
> > +
> > +static struct wmi_driver gigabyte_wmi_driver = {
> > +	.driver = {
> > +		.name = "gigabyte-wmi",
> > +	},
> > +	.id_table = gigabyte_wmi_id_table,
> > +	.probe = gigabyte_wmi_probe,
> > +};
> > +module_wmi_driver(gigabyte_wmi_driver);
> > +
> > +MODULE_DEVICE_TABLE(wmi, gigabyte_wmi_id_table);
> > +MODULE_AUTHOR("Thomas Weißschuh <thomas@...ssschuh.net>");
> > +MODULE_DESCRIPTION("Gigabyte Temperature WMI Driver");
> 
> It's a very minor thing, but could you please
> synchronize this description with the Kconfig?

Of course.

Thanks again for the review!

Thomas