Hello Guenter,
thanks for your feedback.
Am Dienstag, 30. August 2022, 15:43:38 CEST schrieb Guenter Roeck:
> On Mon, May 23, 2022 at 01:05:09PM +0200, Alexander Stein wrote:
> > Instead of comparing the current to the new pwm duty to decide whether to
> > enable the PWM, use a dedicated flag. Also apply the new PWM duty in any
> > case. This is a preparation to enable/disable the regulator dynamically.
> >
> > Signed-off-by: Alexander Stein <alexander.stein@xxxxxxxxxxxxxxx>
> > ---
> >
> > drivers/hwmon/pwm-fan.c | 37 +++++++++++++++++++++++++++++--------
> > 1 file changed, 29 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
> > index 831878daffe6..96b10d422828 100644
> > --- a/drivers/hwmon/pwm-fan.c
> > +++ b/drivers/hwmon/pwm-fan.c
> > @@ -29,10 +29,13 @@ struct pwm_fan_tach {
> >
> > };
> >
> > struct pwm_fan_ctx {
> >
> > + struct device *dev;
> > +
> >
> > struct mutex lock;
> > struct pwm_device *pwm;
> > struct pwm_state pwm_state;
> > struct regulator *reg_en;
> >
> > + bool enabled;
> >
> > int tach_count;
> > struct pwm_fan_tach *tachs;
> >
> > @@ -85,14 +88,21 @@ static void sample_timer(struct timer_list *t)
> >
> > static int pwm_fan_power_on(struct pwm_fan_ctx *ctx)
> > {
> >
> > struct pwm_state *state = &ctx->pwm_state;
> >
> > - unsigned long period;
> >
> > int ret;
> >
> > - period = state->period;
> > - state->duty_cycle = DIV_ROUND_UP(ctx->pwm_value * (period - 1),
> > MAX_PWM);
> > + if (ctx->enabled)
> > + return 0;
> > +
> >
> > state->enabled = true;
> > ret = pwm_apply_state(ctx->pwm, state);
> >
> > + if (ret) {
> > + dev_err(ctx->dev, "failed to enable PWM\n");
> > + goto err;
>
> There is no reason for this goto. Just return directly.
Sure, will do so.
> > + }
> >
> > + ctx->enabled = true;
> > +
> >
> > +err:
> > return ret;
> >
> > }
> >
> > @@ -100,26 +110,36 @@ static int pwm_fan_power_off(struct pwm_fan_ctx
> > *ctx)
> >
> > {
> >
> > struct pwm_state *state = &ctx->pwm_state;
> >
> > + if (!ctx->enabled)
> > + return 0;
> > +
>
> ctx->enabled will initially be false. How is it known that pwm is
> disabled when the driver is loaded ? At the very least that warrants
> an explanation.
I'm not sure what you are concerned about. The PWM is enabled in probe
unconditionally, calling __set_pwm(ctx, MAX_PWM).
> > state->enabled = false;
> > state->duty_cycle = 0;
> > pwm_apply_state(ctx->pwm, state);
>
> This code is a bit inconsistent with pwm_fan_power_on(). Why check for
> error there, but not here ?
You are right, make sense to check in both functions.
Thanks and best regards
Alexander
> > + ctx->enabled = false;
> > +
> >
> > return 0;
> >
> > }
> >
> > static int __set_pwm(struct pwm_fan_ctx *ctx, unsigned long pwm)
> > {
> >
> > + struct pwm_state *state = &ctx->pwm_state;
> > + unsigned long period;
> >
> > int ret = 0;
> >
> > mutex_lock(&ctx->lock);
> >
> > - if (ctx->pwm_value == pwm)
> > - goto exit_set_pwm_err;
> >
> > - if (pwm > 0)
> > + if (pwm > 0) {
> > + period = state->period;
> > + state->duty_cycle = DIV_ROUND_UP(pwm * (period - 1),
MAX_PWM);
> > + ret = pwm_apply_state(ctx->pwm, state);
> > + if (ret)
> > + goto exit_set_pwm_err;
> >
> > ret = pwm_fan_power_on(ctx);
> >
> > - else
> > + } else {
> >
> > ret = pwm_fan_power_off(ctx);
> >
> > -
> > + }
> >
> > if (!ret)
> >
> > ctx->pwm_value = pwm;
> >
> > @@ -326,6 +346,7 @@ static int pwm_fan_probe(struct platform_device *pdev)
> >
> > mutex_init(&ctx->lock);
> >
> > + ctx->dev = &pdev->dev;
> >
> > ctx->pwm = devm_of_pwm_get(dev, dev->of_node, NULL);
> > if (IS_ERR(ctx->pwm))
> >
> > return dev_err_probe(dev, PTR_ERR(ctx->pwm), "Could not
get PWM\n");
