2014-11-03 14:43:19

by Kamil Debski

Subject: [PATCH] hwmon: (pwm-fan) Fix suspend/resume behavior

The state of a PWM output is not clearly defined after resume. Some PWM
drivers do not restore the duty cycle upon resume, thus it is necessary to
manually restore the correct value.

Signed-off-by: Kamil Debski <[email protected]>
---
drivers/hwmon/pwm-fan.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
index 823c877..1991d903 100644
--- a/drivers/hwmon/pwm-fan.c
+++ b/drivers/hwmon/pwm-fan.c
@@ -161,10 +161,17 @@ static int pwm_fan_suspend(struct device *dev)
static int pwm_fan_resume(struct device *dev)
{
struct pwm_fan_ctx *ctx = dev_get_drvdata(dev);
+ unsigned long duty;
+ int ret;

- if (ctx->pwm_value)
- return pwm_enable(ctx->pwm);
- return 0;
+ if (ctx->pwm_value == 0)
+ return 0;
+
+ duty = DIV_ROUND_UP(ctx->pwm_value * (ctx->pwm->period - 1), MAX_PWM);
+ ret = pwm_config(ctx->pwm, duty, ctx->pwm->period);
+ if (ret)
+ return ret;
+ return pwm_enable(ctx->pwm);
}
#endif

--
1.7.9.5

2014-11-03 16:19:35

by Guenter Roeck

Subject: Re: [PATCH] hwmon: (pwm-fan) Fix suspend/resume behavior

On Mon, Nov 03, 2014 at 03:42:55PM +0100, Kamil Debski wrote:
> The state of a PWM output is not clearly defined after resume. Some PWM
> drivers do not restore the duty cycle upon resume, thus it is necessary to
> manually restore the correct value.
>
> Signed-off-by: Kamil Debski <[email protected]>

Applied.

Thanks,
Guenter