Re: [PATCH v1] iio: adc: rockchip_saradc: just get referenced voltage once at probe

["Heiko Stübner" <heiko@sntech.de>]

Hi Simon,

Am Freitag, 6. August 2021, 10:02:44 CEST schrieb Simon Xue:
> From: David Wu <david.wu@rock-chips.com>
> 
> Add voltage notifier, no need to query regulator voltage for
> every saradc read, just get regulator voltage once at probe.
> 
> Signed-off-by: Simon Xue <xxm@rock-chips.com>
> Signed-off-by: David Wu <david.wu@rock-chips.com>

thanks for picking up the suggestion for the regulator notifier :-) .

Please also adapt the commit message to include that information though
and please also increase the versioning ... this definitly isn't v1 ;-) .

One more thing down below.

> ---
>  drivers/iio/adc/rockchip_saradc.c | 35 ++++++++++++++++++++++++-------
>  1 file changed, 28 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/iio/adc/rockchip_saradc.c b/drivers/iio/adc/rockchip_saradc.c
> index f3eb8d2e50dc..d8b0954aeb43 100644
> --- a/drivers/iio/adc/rockchip_saradc.c
> +++ b/drivers/iio/adc/rockchip_saradc.c
> @@ -49,10 +49,12 @@ struct rockchip_saradc {
>  	struct clk		*clk;
>  	struct completion	completion;
>  	struct regulator	*vref;
> +	int			uv_vref;
>  	struct reset_control	*reset;
>  	const struct rockchip_saradc_data *data;
>  	u16			last_val;
>  	const struct iio_chan_spec *last_chan;
> +	struct notifier_block nb;
>  };
>  
>  static void rockchip_saradc_power_down(struct rockchip_saradc *info)
> @@ -105,13 +107,7 @@ static int rockchip_saradc_read_raw(struct iio_dev *indio_dev,
>  		mutex_unlock(&indio_dev->mlock);
>  		return IIO_VAL_INT;
>  	case IIO_CHAN_INFO_SCALE:
> -		ret = regulator_get_voltage(info->vref);
> -		if (ret < 0) {
> -			dev_err(&indio_dev->dev, "failed to get voltage\n");
> -			return ret;
> -		}
> -
> -		*val = ret / 1000;
> +		*val = info->uv_vref / 1000;
>  		*val2 = chan->scan_type.realbits;
>  		return IIO_VAL_FRACTIONAL_LOG2;
>  	default:
> @@ -298,6 +294,19 @@ static irqreturn_t rockchip_saradc_trigger_handler(int irq, void *p)
>  	return IRQ_HANDLED;
>  }
>  
> +static int rockchip_saradc_volt_notify(struct notifier_block *nb,
> +						   unsigned long event,
> +						   void *data)
> +{
> +	struct rockchip_saradc *info =
> +			container_of(nb, struct rockchip_saradc, nb);
> +
> +	if (event & REGULATOR_EVENT_VOLTAGE_CHANGE)
> +		info->uv_vref = (unsigned long)data;
> +
> +	return NOTIFY_OK;
> +}
> +

You probably want an devm-action to unregister the notifier
on device removal. Something like this and the addition in _probe().

static void rockchip_saradc_regulator_action(void *data)
{
	struct rockchip_saradc *info = data;

	regulator_unregister_notifier(info->vref, &info->nb);
}

>  static int rockchip_saradc_probe(struct platform_device *pdev)
>  {
>  	struct rockchip_saradc *info = NULL;
> @@ -410,6 +419,13 @@ static int rockchip_saradc_probe(struct platform_device *pdev)
>  		return ret;
>  	}
>  
> +	info->uv_vref = regulator_get_voltage(info->vref);
> +	if (info->uv_vref < 0) {
> +		dev_err(&pdev->dev, "failed to get voltage\n");
> +		ret = info->uv_vref;
> +		return ret;
> +	}
> +
>  	ret = clk_prepare_enable(info->pclk);
>  	if (ret < 0) {
>  		dev_err(&pdev->dev, "failed to enable pclk\n");
> @@ -450,6 +466,11 @@ static int rockchip_saradc_probe(struct platform_device *pdev)
>  	if (ret)
>  		return ret;
>  
> +	info->nb.notifier_call = rockchip_saradc_volt_notify;
> +	ret = regulator_register_notifier(info->vref, &info->nb);
> +	if (ret)
> +		return ret;
> +

	ret = devm_add_action_or_reset(&pdev->dev, rockchip_saradc_regulator_action, info);
	if (ret)
		goto ret;

This ties the unregistration nicely into the devm-framework and thus
doesn't require any additional error handling, as the "action" is also
directly called if devm_add_action fails.


Heiko

>  	return devm_iio_device_register(&pdev->dev, indio_dev);
>  }
>  
>