From: Armin Wolf <W_Armin@xxxxxx> commit c0d79987a0d82671bff374c07f2201f9bdf4aaa2 upstream. When setting the fan speed, i8k_set_fan() calls i8k_get_fan_status(), causing an unnecessary SMM call since from the two users of this function, only i8k_ioctl_unlocked() needs to know the new fan status while dell_smm_write() ignores the new fan status. Since SMM calls can be very slow while also making error reporting difficult for dell_smm_write(), remove the function call from i8k_set_fan() and call it separately in i8k_ioctl_unlocked(). Tested on a Dell Inspiron 3505. Signed-off-by: Armin Wolf <W_Armin@xxxxxx> Reviewed-by: Pali Rohár <pali@xxxxxxxxxx> Link: https://lore.kernel.org/r/20211021190531.17379-6-W_Armin@xxxxxx Signed-off-by: Guenter Roeck <linux@xxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/hwmon/dell-smm-hwmon.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) --- a/drivers/hwmon/dell-smm-hwmon.c +++ b/drivers/hwmon/dell-smm-hwmon.c @@ -294,7 +294,7 @@ static int i8k_get_fan_nominal_speed(int } /* - * Set the fan speed (off, low, high). Returns the new fan status. + * Set the fan speed (off, low, high, ...). */ static int i8k_set_fan(int fan, int speed) { @@ -303,7 +303,7 @@ static int i8k_set_fan(int fan, int spee speed = (speed < 0) ? 0 : ((speed > i8k_fan_max) ? i8k_fan_max : speed); regs.ebx = (fan & 0xff) | (speed << 8); - return i8k_smm(®s) ? : i8k_get_fan_status(fan); + return i8k_smm(®s); } static int i8k_get_temp_type(int sensor) @@ -417,7 +417,7 @@ static int i8k_ioctl_unlocked(struct file *fp, unsigned int cmd, unsigned long arg) { int val = 0; - int speed; + int speed, err; unsigned char buff[16]; int __user *argp = (int __user *)arg; @@ -478,7 +478,11 @@ i8k_ioctl_unlocked(struct file *fp, unsi if (copy_from_user(&speed, argp + 1, sizeof(int))) return -EFAULT; - val = i8k_set_fan(val, speed); + err = i8k_set_fan(val, speed); + if (err < 0) + return err; + + val = i8k_get_fan_status(val); break; default:
