Before commit 86585c61972f ("hwmon: (pwm-fan) stop using legacy PWM functions and some cleanups") pwm_apply_state() was called unconditionally in pwm_fan_probe(). In this commit this direct call was replaced by a call to __set_pwm(ct, MAX_PWM) which however is a noop if ctx->pwm_value already matches the value to set. After probe the fan is supposed to run at full speed, and the internal driver state suggests it does, but this isn't asserted and depending on bootloader and pwm low-level driver, the fan might just be off. So drop setting pwm_value to MAX_PWM to ensure the check in __set_pwm doesn't make it exit early and the fan goes on as intended.
Cc: stable@vger.kernel.org Fixes: 86585c61972f ("hwmon: (pwm-fan) stop using legacy PWM functions and some cleanups") Signed-off-by: Billy Tsai billy_tsai@aspeedtech.com --- drivers/hwmon/pwm-fan.c | 2 -- 1 file changed, 2 deletions(-)
diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c index 17518b4cab1b..f12b9a28a232 100644 --- a/drivers/hwmon/pwm-fan.c +++ b/drivers/hwmon/pwm-fan.c @@ -336,8 +336,6 @@ static int pwm_fan_probe(struct platform_device *pdev) return ret; }
- ctx->pwm_value = MAX_PWM; - pwm_init_state(ctx->pwm, &ctx->pwm_state);
/*
On Tue, Nov 30, 2021 at 05:22:12PM +0800, Billy Tsai wrote:
Before commit 86585c61972f ("hwmon: (pwm-fan) stop using legacy PWM functions and some cleanups") pwm_apply_state() was called unconditionally in pwm_fan_probe(). In this commit this direct call was replaced by a call to __set_pwm(ct, MAX_PWM) which however is a noop if ctx->pwm_value already matches the value to set. After probe the fan is supposed to run at full speed, and the internal driver state suggests it does, but this isn't asserted and depending on bootloader and pwm low-level driver, the fan might just be off. So drop setting pwm_value to MAX_PWM to ensure the check in __set_pwm doesn't make it exit early and the fan goes on as intended.
Cc: stable@vger.kernel.org Fixes: 86585c61972f ("hwmon: (pwm-fan) stop using legacy PWM functions and some cleanups") Signed-off-by: Billy Tsai billy_tsai@aspeedtech.com
Nice commit log :-)
Reviewed-by: Uwe Kleine-König u.kleine-koenig@pengutronix.de
Best regards Uwe
On 11/30/21 1:22 AM, Billy Tsai wrote:
Before commit 86585c61972f ("hwmon: (pwm-fan) stop using legacy PWM functions and some cleanups") pwm_apply_state() was called unconditionally in pwm_fan_probe(). In this commit this direct call was replaced by a call to __set_pwm(ct, MAX_PWM) which however is a noop if ctx->pwm_value already matches the value to set. After probe the fan is supposed to run at full speed, and the internal driver state suggests it does, but this isn't asserted and depending on bootloader and pwm low-level driver, the fan might just be off. So drop setting pwm_value to MAX_PWM to ensure the check in __set_pwm doesn't make it exit early and the fan goes on as intended.
Cc: stable@vger.kernel.org Fixes: 86585c61972f ("hwmon: (pwm-fan) stop using legacy PWM functions and some cleanups") Signed-off-by: Billy Tsai billy_tsai@aspeedtech.com
I'll apply this patch, but _please_ version your patches in the future and provide a change log.
Guenter
drivers/hwmon/pwm-fan.c | 2 -- 1 file changed, 2 deletions(-)
diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c index 17518b4cab1b..f12b9a28a232 100644 --- a/drivers/hwmon/pwm-fan.c +++ b/drivers/hwmon/pwm-fan.c @@ -336,8 +336,6 @@ static int pwm_fan_probe(struct platform_device *pdev) return ret; }
- ctx->pwm_value = MAX_PWM;
- pwm_init_state(ctx->pwm, &ctx->pwm_state);
/*
linux-stable-mirror@lists.linaro.org
-
Billy Tsai -
Guenter Roeck -
Uwe Kleine-König