Re: [PATCH v3] i8k: Autodetect maximal fan speed and fan RPM multiplier

Guenter Roeck
2014-12-21T11:57:39Z

On 12/21/2014 01:20 AM, Pali Rohár wrote:
> This patch adds new function i8k_get_fan_nominal_speed() for doing SMM call
> which will return nominal fan RPM for specified fan speed. It returns nominal
> RPM value at which fan operate when speed (0, 1, 2, 3) is set. It looks like
> RPM value is not accurate, but still provides very useful information.
>
> First it can be used to validate if certain fan speed could be accepted by SMM
> for setting fan speed and we can use this routine to detect maximal fan speed.
>
> Second it returns RPM value, so we can check if value looks correct with
> multiplier 30 or multiplier 1 (until now only these two multiplier were used).
> If RPM value with multiplier 30 is too high, then multiplier 1 is used.
>
> In case when SMM reports that new function is not supported we will fallback
> to old hardcoded values. Maximal fan speed would be 2 and RPM multiplier 30.
>
> Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
> Tested-by: Pali Rohár <pali.rohar@gmail.com>
> ---
> drivers/char/i8k.c | 89 ++++++++++++++++++++++++++++++++++++++++++++--------
> 1 file changed, 76 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/char/i8k.c b/drivers/char/i8k.c
> index 48d701c..ce2147c 100644
> --- a/drivers/char/i8k.c
> +++ b/drivers/char/i8k.c
> @@ -6,6 +6,7 @@
> * Hwmon integration:
> * Copyright (C) 2011 Jean Delvare <jdelvare@suse.de>
> * Copyright (C) 2013, 2014 Guenter Roeck <linux@roeck-us.net>
> + * Copyright (C) 2014 Pali Rohár <pali.rohar@gmail.com>
> *
> * This program is free software; you can redistribute it and/or modify it
> * under the terms of the GNU General Public License as published by the
> @@ -42,12 +43,13 @@
> #define I8K_SMM_SET_FAN 0x01a3
> #define I8K_SMM_GET_FAN 0x00a3
> #define I8K_SMM_GET_SPEED 0x02a3
> +#define I8K_SMM_GET_NOM_SPEED 0x04a3
> #define I8K_SMM_GET_TEMP 0x10a3
> #define I8K_SMM_GET_TEMP_TYPE 0x11a3
> #define I8K_SMM_GET_DELL_SIG1 0xfea3
> #define I8K_SMM_GET_DELL_SIG2 0xffa3
>
> -#define I8K_FAN_MULT 30
> +#define I8K_FAN_MAX_RPM 30000
> #define I8K_MAX_TEMP 127
>
> #define I8K_FN_NONE 0x00
> @@ -64,7 +66,7 @@ static DEFINE_MUTEX(i8k_mutex);
> static char bios_version[4];
> static struct device *i8k_hwmon_dev;
> static u32 i8k_hwmon_flags;
> -static int i8k_fan_mult;
> +static int i8k_fan_mult = 30;

Why did you drop I8K_FAN_MULT ?

> static int i8k_pwm_mult;
> static int i8k_fan_max = I8K_FAN_HIGH;
>
> @@ -95,13 +97,13 @@ static bool power_status;
> module_param(power_status, bool, 0600);
> MODULE_PARM_DESC(power_status, "Report power status in /proc/i8k");
>
> -static int fan_mult = I8K_FAN_MULT;
> +static int fan_mult;
> module_param(fan_mult, int, 0);
> -MODULE_PARM_DESC(fan_mult, "Factor to multiply fan speed with");
> +MODULE_PARM_DESC(fan_mult, "Factor to multiply fan speed with (default: autodetect)");
>
> -static int fan_max = I8K_FAN_HIGH;
> +static int fan_max;
> module_param(fan_max, int, 0);
> -MODULE_PARM_DESC(fan_max, "Maximum configurable fan speed");
> +MODULE_PARM_DESC(fan_max, "Maximum configurable fan speed (default: autodetect)");
>
> static int i8k_open_fs(struct inode *inode, struct file *file);
> static long i8k_ioctl(struct file *, unsigned int, unsigned long);
> @@ -276,6 +278,17 @@ static int i8k_get_fan_speed(int fan)
> }
>
> /*
> + * Read the fan nominal rpm for specific fan speed.
> + */
> +static int i8k_get_fan_nominal_speed(int fan, int speed)
> +{
> + struct smm_regs regs = { .eax = I8K_SMM_GET_NOM_SPEED, };
> +
> + regs.ebx = (fan & 0xff) | (speed << 8);
> + return i8k_smm(&regs) ? : (regs.eax & 0xffff) * i8k_fan_mult;
> +}
> +
> +/*
> * Set the fan speed (off, low, high). Returns the new fan status.
> */
> static int i8k_set_fan(int fan, int speed)
> @@ -854,7 +867,9 @@ MODULE_DEVICE_TABLE(dmi, i8k_dmi_table);
> */
> static int __init i8k_probe(void)
> {
> + const struct i8k_config_data *conf;

Why did you move this variable declaration ?

> const struct dmi_system_id *id;
> + int fan, val, ret;
>
> /*
> * Get DMI information
> @@ -883,19 +898,67 @@ static int __init i8k_probe(void)
> return -ENODEV;
> }
>
> - i8k_fan_mult = fan_mult;
> - i8k_fan_max = fan_max ? : I8K_FAN_HIGH; /* Must not be 0 */
> + /*
> + * Autodetect fan multiplier and maximal fan speed from dmi config
> + * Values specified in module parameters override values from dmi
> + */
> id = dmi_first_match(i8k_dmi_table);
> if (id && id->driver_data) {
> - const struct i8k_config_data *conf = id->driver_data;
> + conf = id->driver_data;
> + if (fan_mult <= 0 && conf->fan_mult > 0)

I still don't see the value in accepting fan_mult < 0 (compeared to == 0).

> + fan_mult = conf->fan_mult;
> + if (fan_max <= 0 && conf->fan_max > 0)

Same for fan_max < 0.

> + fan_max = conf->fan_max;
> + }
>
> - if (fan_mult == I8K_FAN_MULT && conf->fan_mult)
> - i8k_fan_mult = conf->fan_mult;
> - if (fan_max == I8K_FAN_HIGH && conf->fan_max)
> - i8k_fan_max = conf->fan_max;
> + if (fan_max <= 0) {

Same here.

> + /*
> + * Autodetect maximal fan speed value
> + * Speed value is valid if i8k_get_fan_nominal_speed() not fail
> + */
> + for (fan = 0; fan < 2; ++fan) {
> + for (val = 1; val < 256; ++val) {
> + if (i8k_get_fan_nominal_speed(fan, val) < 0)
> + break;
> + fan_max = val; /* Must not be 0 */
> + }
> + if (fan_max != 0) {
> + i8k_fan_max = fan_max;
> + break;
> + }
> + }
> + } else {
> + /* Maximal fan speed was specified in module param or in dmi */
> + i8k_fan_max = fan_max;
> }
> +
> i8k_pwm_mult = DIV_ROUND_UP(255, i8k_fan_max);
>
> + if (fan_mult <= 0) {

Same here.

Thanks,
Guenter