Re: [PATCH 2/3] i8k: Autodetect maximal fan speed and fan RPM multiplier

Pali Rohár
2014-12-09T20:23:29Z

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On Tuesday 09 December 2014 21:20:23 Guenter Roeck wrote:
> On Tue, Dec 09, 2014 at 09:07:00PM +0100, Pali Rohár wrote:
> > This patch adds new function i8k_get_fan_nominal_rpm() 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 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 was 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>
> > ---
> > I tested this patch only on my Dell Latitude E6440 and
> > autodetection worked fine Before appying this patch it
> > should be tested on some other dell machines too but if
> > machine does not support i8k_get_fan_nominal_rpm() driver
> > should fallback to old values. So patch should be without
> > regressions.
>
> It looks like many of your error checks are unnecessary.
> Why did you add those ?
>
> Please refrain from adding unnecessary code.
>
> Guenter
>

Which error checks do you mean?

> > ---
> >
> > drivers/char/i8k.c | 122
> > ++++++++++++++++++++++++++++++++++++++--------
> > include/uapi/linux/i8k.h | 4 +-
> > 2 files changed, 104 insertions(+), 22 deletions(-)
> >
> > diff --git a/drivers/char/i8k.c b/drivers/char/i8k.c
> > index 31e4beb..8bdbed2 100644
> > --- a/drivers/char/i8k.c
> > +++ b/drivers/char/i8k.c
> > @@ -42,12 +42,14 @@
> >
> > #define I8K_SMM_GET_FAN_SPEED 0x00a3
> > #define I8K_SMM_SET_FAN_SPEED 0x01a3
> > #define I8K_SMM_GET_FAN_RPM 0x02a3
> >
> > +#define I8K_SMM_GET_FAN_NOM_RPM 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_DEFAULT_MULT 30
> > +#define I8K_FAN_MAX_RPM 30000
> >
> > #define I8K_MAX_TEMP 127
> >
> > #define I8K_FN_NONE 0x00
> >
> > @@ -64,9 +66,9 @@ 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_pwm_mult;
> > -static int i8k_fan_max = I8K_FAN_HIGH;
> > +static int i8k_fan_mult[I8K_FAN_COUNT];
> > +static int i8k_pwm_mult[I8K_FAN_COUNT];
> > +static int i8k_fan_max[I8K_FAN_COUNT];
> >
> > #define I8K_HWMON_HAVE_TEMP1 (1 << 0)
> > #define I8K_HWMON_HAVE_TEMP2 (1 << 1)
> >
> > @@ -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 rpm
> > with"); +MODULE_PARM_DESC(fan_mult, "Factor to multiply fan
> > rpm 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);
> >
> > @@ -271,8 +273,25 @@ static int i8k_get_fan_rpm(int fan)
> >
> > {
> >
> > struct smm_regs regs = { .eax = I8K_SMM_GET_FAN_RPM, };
> >
> > + if (fan < 0 || fan >= I8K_FAN_COUNT)
> > + return -EINVAL;
> > +
> >
> > regs.ebx = fan & 0xff;
> >
> > - return i8k_smm(&regs) ? : (regs.eax & 0xffff) *
> > i8k_fan_mult; + return i8k_smm(&regs) ? : (regs.eax &
> > 0xffff) * i8k_fan_mult[fan]; +}
> > +
> > +/*
> > + * Read the fan nominal rpm for specific fan speed.
> > + */
> > +static int i8k_get_fan_nominal_rpm(int fan, int speed)
> > +{
> > + struct smm_regs regs = { .eax = I8K_SMM_GET_FAN_NOM_RPM,
> > }; +
> > + if (fan < 0 || fan >= I8K_FAN_COUNT)
> > + return -EINVAL;
> > +
> > + regs.ebx = (fan & 0xff) | (speed << 8);
> > + return i8k_smm(&regs) ? : (regs.eax & 0xffff) *
> > i8k_fan_mult[fan];
> >
> > }
> >
> > /*
> >
> > @@ -282,9 +301,12 @@ static int i8k_set_fan_speed(int fan,
> > int speed)
> >
> > {
> >
> > struct smm_regs regs = { .eax = I8K_SMM_SET_FAN_SPEED, };
> >
> > - speed = (speed < 0) ? 0 : ((speed > i8k_fan_max) ?
> > i8k_fan_max : speed); - regs.ebx = (fan & 0xff) | (speed <<
> > 8);
> > + if (speed < 0)
> > + speed = 0;
> > + if (fan >= 0 && fan < I8K_FAN_COUNT && speed >
> > i8k_fan_max[fan]) + speed = i8k_fan_max[fan];
> >
> > + regs.ebx = (fan & 0xff) | (speed << 8);
> >
> > return i8k_smm(&regs) ? : i8k_get_fan_speed(fan);
> >
> > }
> >
> > @@ -559,10 +581,14 @@ static ssize_t
> > i8k_hwmon_show_pwm(struct device *dev,
> >
> > int index = to_sensor_dev_attr(devattr)->index;
> > int fan_speed;
> >
> > + if (index < 0 || index >= I8K_FAN_COUNT)
> > + return -EINVAL;
> > +
> >
> > fan_speed = i8k_get_fan_speed(index);
> > if (fan_speed < 0)
> >
> > return -EIO;
> >
> > - return sprintf(buf, "%d\n", clamp_val(fan_speed *
> > i8k_pwm_mult, 0, 255)); + return sprintf(buf, "%d\n",
> > clamp_val(fan_speed * i8k_pwm_mult[index], +
0,
> > 255));
> >
> > }
> >
> > static ssize_t i8k_hwmon_set_pwm(struct device *dev,
> >
> > @@ -573,10 +599,14 @@ static ssize_t
> > i8k_hwmon_set_pwm(struct device *dev,
> >
> > unsigned long val;
> > int err;
> >
> > + if (index < 0 || index >= I8K_FAN_COUNT)
> > + return -EINVAL;
> > +
> >
> > err = kstrtoul(buf, 10, &val);
> > if (err)
> >
> > return err;
> >
> > - val = clamp_val(DIV_ROUND_CLOSEST(val, i8k_pwm_mult), 0,
> > i8k_fan_max); + val = clamp_val(DIV_ROUND_CLOSEST(val,
> > i8k_pwm_mult[index]), 0, + i8k_fan_max[index]);
> >
> > mutex_lock(&i8k_mutex);
> > err = i8k_set_fan_speed(index, val);
> >
> > @@ -854,7 +884,9 @@ MODULE_DEVICE_TABLE(dmi, i8k_dmi_table);
> >
> > */
> >
> > static int __init i8k_probe(void)
> > {
> >
> > + const struct i8k_config_data *conf;
> >
> > const struct dmi_system_id *id;
> >
> > + int fan, val, ret;
> >
> > /*
> >
> > * Get DMI information
> >
> > @@ -883,18 +915,66 @@ 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)
> > + fan_mult = conf->fan_mult;
> > + if (fan_max <= 0 && conf->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_mult <= 0) {
> > + /*
> > + * Autodetect fan multiplier for each fan based on
> > nominal rpm + * First set default fan multiplier for each
> > fan + * And if it reports rpm value too high then set
> > multiplier to 1 + */
> > + for (fan = 0; fan < I8K_FAN_COUNT; ++fan) {
> > + i8k_fan_mult[fan] = I8K_FAN_DEFAULT_MULT;
> > + for (val = 0; val < 256; ++val) {
> > + ret = i8k_get_fan_nominal_rpm(fan, val);
> > + if (ret > I8K_FAN_MAX_RPM) {
> > + i8k_fan_mult[fan] = 1;
> > + break;
> > + } else if (ret < 0) {
> > + break;
> > + }
> > + }
> > + }
> > + } else {
> > + /* Fan multiplier was specified in module param or in
dmi
> > */ + for (fan = 0; fan < I8K_FAN_COUNT; ++fan)
> > + i8k_fan_mult[fan] = fan_mult;
> >
> > }
> >
> > - i8k_pwm_mult = DIV_ROUND_UP(255, i8k_fan_max);
> > +
> > + if (fan_max <= 0) {
> > + /*
> > + * Autodetect maximal fan speed value for each fan
> > + * Speed value is valid if i8k_get_fan_nominal_rpm()
not
> > fail + */
> > + for (fan = 0; fan < I8K_FAN_COUNT; ++fan) {
> > + for (val = 0; val < 256; ++val) {
> > + if (i8k_get_fan_nominal_rpm(fan, val) < 0)
> > + break;
> > + }
> > + --val; /* set last value which not failed */
> > + if (val <= 0) /* Must not be 0 (and non negative)
*/
> > + val = I8K_FAN_HIGH;
> > + i8k_fan_max[fan] = val;
> > + }
> > + } else {
> > + /* Maximal fan speed was specified in module param or
in
> > dmi */ + for (fan = 0; fan < I8K_FAN_COUNT; ++fan)
> > + i8k_fan_max[fan] = fan_max;
> > + }
> > +
> > + for (fan = 0; fan < I8K_FAN_COUNT; ++fan)
> > + i8k_pwm_mult[fan] = DIV_ROUND_UP(255,
i8k_fan_max[fan]);
> >
> > return 0;
> >
> > }
> >
> > diff --git a/include/uapi/linux/i8k.h
> > b/include/uapi/linux/i8k.h index 133d02f..60ef0ea 100644
> > --- a/include/uapi/linux/i8k.h
> > +++ b/include/uapi/linux/i8k.h
> > @@ -29,8 +29,10 @@
> >
> > #define I8K_GET_FAN _IOWR('i', 0x86, size_t)
> > #define I8K_SET_FAN _IOWR('i', 0x87, size_t)
> >
> > -#define I8K_FAN_LEFT 1
> >
> > #define I8K_FAN_RIGHT 0
> >
> > +#define I8K_FAN_LEFT 1
> > +#define I8K_FAN_COUNT (I8K_FAN_LEFT + 1)
> > +
> >
> > #define I8K_FAN_OFF 0
> > #define I8K_FAN_LOW 1
> > #define I8K_FAN_HIGH 2

--
Pali Rohár
pali.rohar@gmail.com

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