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

    > ---
    > 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
    > --
    > 1.7.9.5
    >


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