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().

This patch was originally a performance optimization, but it turned out a user with a buggy machine requires this patch since it also fixes error reporting when i8k_get_fan_status fails. https://github.com/lm-sensors/lm-sensors/pull/383

Tested on a Dell Inspiron 3505.

Cc: stable@vger.kernel.org # 5.15.x Signed-off-by: Armin Wolf W_Armin@gmx.de --- drivers/hwmon/dell-smm-hwmon.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/hwmon/dell-smm-hwmon.c b/drivers/hwmon/dell-smm-hwmon.c index 47fce97996de..9cb1c3588038 100644 --- a/drivers/hwmon/dell-smm-hwmon.c +++ b/drivers/hwmon/dell-smm-hwmon.c @@ -326,7 +326,7 @@ static int i8k_enable_fan_auto_mode(const struct dell_smm_data *data, bool enabl }

/* - * Set the fan speed (off, low, high). Returns the new fan status. + * Set the fan speed (off, low, high, ...). */ static int i8k_set_fan(const struct dell_smm_data *data, int fan, int speed) { @@ -338,7 +338,7 @@ static int i8k_set_fan(const struct dell_smm_data *data, int fan, int speed) speed = (speed < 0) ? 0 : ((speed > data->i8k_fan_max) ? data->i8k_fan_max : speed); regs.ebx = (fan & 0xff) | (speed << 8);

- return i8k_smm(&regs) ? : i8k_get_fan_status(data, fan); + return i8k_smm(&regs); }

static int __init i8k_get_temp_type(int sensor) @@ -452,7 +452,7 @@ static int i8k_ioctl_unlocked(struct file *fp, struct dell_smm_data *data, unsigned int cmd, unsigned long arg) { int val = 0; - int speed; + int speed, err; unsigned char buff[16]; int __user *argp = (int __user *)arg;

@@ -513,7 +513,11 @@ i8k_ioctl_unlocked(struct file *fp, struct dell_smm_data *data, unsigned int cmd if (copy_from_user(&speed, argp + 1, sizeof(int))) return -EFAULT;

- val = i8k_set_fan(data, val, speed); + err = i8k_set_fan(data, val, speed); + if (err < 0) + return err; + + val = i8k_get_fan_status(data, val); break;

default: -- 2.30.2