Re: [PATCH] platform/x86/lenovo: thinkpad_acpi: add named speed presets to fan_write_cmd_speed

[Mark Pearson]

Hi Daniil

On Mon, Mar 30, 2026, at 4:35 PM, Даниил Булгарь wrote:
> platform/x86/lenovo: thinkpad_acpi: add named speed presets to
> fan_write_cmd_speed
>
> The fan_write_cmd_speed() function had a TODO comment suggesting
> support for named speed presets (low, medium, high). Implement
> this by mapping the preset names to the existing fan_speed_presets
> enum values, following the same strstarts() pattern used in
> fan_write_cmd_level().
> Signed-off-by: Daniil Bulgar <bulgardaniil18@xxxxxxxxx>
> ---
>  drivers/platform/x86/lenovo/thinkpad_acpi.c | 17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/platform/x86/lenovo/thinkpad_acpi.c
> b/drivers/platform/x86/lenovo/thinkpad_acpi.c
> index 8982d92df..f10cebe11 100644
> --- a/drivers/platform/x86/lenovo/thinkpad_acpi.c
> +++ b/drivers/platform/x86/lenovo/thinkpad_acpi.c
> @@ -7957,6 +7957,12 @@ enum fan_control_commands {
>                          * and also watchdog cmd */
>  };
>
> +enum fan_speed_preset {
> +    TPACPI_FAN_SPEED_LOW    = 65535 / 4,    /* 25% speed */
> +    TPACPI_FAN_SPEED_MEDIUM    = 65535 / 2,    /* 50% speed */
> +    TPACPI_FAN_SPEED_HIGH    = 65535,    /* 100% speed */
> +};
> +
>  static bool fan_control_allowed;
>
>  static enum fan_status_access_mode fan_status_access_mode;
> @@ -9249,10 +9255,13 @@ static int fan_write_cmd_speed(const char *cmd, int *rc)
>  {
>      int speed;
>
> -    /* TODO:
> -    * Support speed <low> <medium> <high> ? */
> -
> -    if (sscanf(cmd, "speed %d", &speed) != 1)
> +    if (strstarts(cmd, "speed low"))
> +        speed = TPACPI_FAN_SPEED_LOW;
> +    else if (strstarts(cmd, "speed medium"))
> +        speed = TPACPI_FAN_SPEED_MEDIUM;
> +    else if (strstarts(cmd, "speed high"))
> +        speed = TPACPI_FAN_SPEED_HIGH;
> +    else if (sscanf(cmd, "speed %d", &speed) != 1)
>          return 0;
>
>      *rc = fan_set_speed(speed);
> -- 
> 2.53.0

I'd never noticed that TODO :)

No issues with the code but I'd like to check with the thermal team if those are better ways of determining the ranges. I've got a feeling that they probably aren't. 
Fans don't go that high (or low) during operation so I wonder if there are better 'ranges' to be used (though it might be platform dependent too)

I'll ask if there is any guidance on it.

Mark