Re: [PATCH v10] hwmon: (yogafan) Add support for Lenovo Yoga/Legion fan monitoring

[Guenter Roeck]

Hi Sergio,

On 3/26/26 18:29, Sergio Melas wrote:
> To address low-resolution sampling in the Lenovo EC firmware, the
> driver implements a Rate-Limited Lag (RLLag) filter using a passive
> discrete-time first-order model. This ensures physical consistency
> of the RPM signal regardless of userspace polling rates.
>
> Concerning youd doubt:
> Sorry, you lost me a bit. Isn't that already implemented in v8 ?
>
> V8 had the logic, but V9 adds the extensive database and documentation
> (see yogafan.rst) to guarantee all ACPI paths and 8/16-bit multipliers
> are correctly mapped.
>
> Please disregard the previous v9 submission. It was incorrectly formatted
> as an incremental diff; this version (v9/v10) is a complete standalone
> patch for clean application.
> Apologies for the noise.

I didn't realize, but the above is really not an appropriate patch description.
Please follow Documentation/process/submitting-patches.rst for a more
appropriate description.

Also, I noticed that you send new versions of your patch as reply to previous
versions. Please don't do that. Again, please see the guidelines for submitting
patches.

Additional comments below.

> Signed-off-by: Sergio Melas <sergiomelas@xxxxxxxxx>
>
> ---
[...]
> +===============================================================================================
> +LENOVO FAN CONTROLLER: MASTER REFERENCE DATABASE (2026)
> +===============================================================================================
> +
> +MODEL (DMI PN) | FAMILY / SERIES  | EC OFFSET | FULL ACPI OBJECT PATH          | WIDTH  | MULTiplier
> +-----------------------------------------------------------------------------------------------

I think 0-day complains because the length of the underline string does not match
the length of the description.

> +82N7           | Yoga 14cACN      | 0x06      | \_SB.PCI0.LPC0.EC0.FANS        |  8-bit | 100
> +80V2 / 81C3    | Yoga 710/720     | 0x06      | \_SB.PCI0.LPC0.EC0.FAN0        |  8-bit | 100
> +83E2 / 83DN    | Yoga Pro 7/9     | 0xFE      | \_SB.PCI0.LPC0.EC0.FANS        |  8-bit | 100
> +82A2 / 82A3    | Yoga Slim 7      | 0x06      | \_SB.PCI0.LPC0.EC0.FANS        |  8-bit | 100
> +81YM / 82FG    | IdeaPad 5        | 0x06      | \_SB.PCI0.LPC0.EC0.FAN0        |  8-bit | 100
> +82JW / 82JU    | Legion 5 (AMD)   | 0xFE/0xFF | \_SB.PCI0.LPC0.EC0.FANS (Fan1) | 16-bit | 1
> +82JW / 82JU    | Legion 5 (AMD)   | 0xFE/0xFF | \_SB.PCI0.LPC0.EC0.FA2S (Fan2) | 16-bit | 1
> +82WQ           | Legion 7i (Int)  | 0xFE/0xFF | \_SB.PCI0.LPC0.EC0.FANS (Fan1) | 16-bit | 1
> +82WQ           | Legion 7i (Int)  | 0xFE/0xFF | \_SB.PCI0.LPC0.EC0.FA2S (Fan2) | 16-bit | 1
> +82XV / 83DV    | LOQ 15/16        | 0xFE/0xFF | \_SB.PCI0.LPC0.EC0.FANS /FA2S  | 16-bit | 1
> +83AK           | ThinkBook G6     | 0x06      | \_SB.PCI0.LPC0.EC0.FAN0        |  8-bit | 100
> +81X1           | Flex 5           | 0x06      | \_SB.PCI0.LPC0.EC0.FAN0        |  8-bit | 100
> +*Legacy*       | Pre-2020 Models  | 0x06      | \_SB.PCI0.LPC.EC.FAN0          |  8-bit | 100

Since this is known based on the model,

[ ...]
> +static int yoga_fan_probe(struct platform_device *pdev)
> +{
> +	const struct dmi_system_id *dmi_id;
> +	const struct yogafan_config *cfg;
> +	struct yoga_fan_data *data;
> +	struct device *hwmon_dev;
> +	acpi_handle handle;
> +	int i;
> +	static const char * const fan_paths[] = {
> +		"\\_SB.PCI0.LPC0.EC0.FANS",  /* Primary Fan (Yoga) */
> +		"\\_SB.PCI0.LPC0.EC0.FA2S",  /* Secondary Fan (Legion / LOQ) */
> +		"\\_SB.PCI0.LPC0.EC0.FAN0",  /* IdeaPad / Slim / Flex */
> +		"\\_SB.PCI0.LPC.EC.FAN0",    /* Legacy (pre-2020 models) */
> +		"\\_SB.PCI0.LPC0.EC.FAN0",   /* Alternate (Certain Slim/Flex) */
> +	};

Is this table even necessary ? It should be possible to identify the supported ACPI
object path(s) from the DMI table entry.

Thanks,
Guenter