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.
> + }
>
> + 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.
> 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 ?
>
> + 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");
