Subject: [PATCH 3/3] iio: adc: stm32-adc: switch off running adc when going to low power

From: [email-masked] (Jonathan Cameron)
Date: Sun, 25 Nov 2018 13:17:35 +0000

On Tue, 20 Nov 2018 11:12:32 +0100
Fabrice Gasnier <[email-masked]> wrote:

> Switch off ADC when going to low power mode, in case it has been left
> running in buffer mode. Then re-enable it when resuming.
> 
> Signed-off-by: Fabrice Gasnier <[email-masked]>
My suspicion is that we have other drivers not correctly handing this
case, but as far as I can see you have it well covered here.

Applied to the togreg branch of iio.git and pushed out as testing
for the autobuilders to play with it.

Thanks,

Jonathan

> ---
>  drivers/iio/adc/stm32-adc.c | 79 ++++++++++++++++++++++++++++++++++++---------
>  1 file changed, 63 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
> index 32c9c61..2a9891c 100644
> --- a/drivers/iio/adc/stm32-adc.c
> +++ b/drivers/iio/adc/stm32-adc.c
> @@ -1518,7 +1518,7 @@ static int stm32_adc_dma_start(struct iio_dev *indio_dev)
>  	return 0;
>  }
>  
> -static int stm32_adc_buffer_postenable(struct iio_dev *indio_dev)
> +static int __stm32_adc_buffer_postenable(struct iio_dev *indio_dev)
>  {
>  	struct stm32_adc *adc = iio_priv(indio_dev);
>  	struct device *dev = indio_dev->dev.parent;
> @@ -1542,10 +1542,6 @@ static int stm32_adc_buffer_postenable(struct iio_dev *indio_dev)
>  		goto err_clr_trig;
>  	}
>  
> -	ret = iio_triggered_buffer_postenable(indio_dev);
> -	if (ret < 0)
> -		goto err_stop_dma;
> -
>  	/* Reset adc buffer index */
>  	adc->bufi = 0;
>  
> @@ -1556,9 +1552,6 @@ static int stm32_adc_buffer_postenable(struct iio_dev *indio_dev)
>  
>  	return 0;
>  
> -err_stop_dma:
> -	if (adc->dma_chan)
> -		dmaengine_terminate_all(adc->dma_chan);
>  err_clr_trig:
>  	stm32_adc_set_trig(indio_dev, NULL);
>  err_pm_put:
> @@ -1568,20 +1561,30 @@ static int stm32_adc_buffer_postenable(struct iio_dev *indio_dev)
>  	return ret;
>  }
>  
> -static int stm32_adc_buffer_predisable(struct iio_dev *indio_dev)
> +static int stm32_adc_buffer_postenable(struct iio_dev *indio_dev)
> +{
> +	int ret;
> +
> +	ret = iio_triggered_buffer_postenable(indio_dev);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = __stm32_adc_buffer_postenable(indio_dev);
> +	if (ret < 0)
> +		iio_triggered_buffer_predisable(indio_dev);
> +
> +	return ret;
> +}
> +
> +static void __stm32_adc_buffer_predisable(struct iio_dev *indio_dev)
>  {
>  	struct stm32_adc *adc = iio_priv(indio_dev);
>  	struct device *dev = indio_dev->dev.parent;
> -	int ret;
>  
>  	adc->cfg->stop_conv(adc);
>  	if (!adc->dma_chan)
>  		stm32_adc_conv_irq_disable(adc);
>  
> -	ret = iio_triggered_buffer_predisable(indio_dev);
> -	if (ret < 0)
> -		dev_err(&indio_dev->dev, "predisable failed\n");
> -
>  	if (adc->dma_chan)
>  		dmaengine_terminate_all(adc->dma_chan);
>  
> @@ -1590,6 +1593,17 @@ static int stm32_adc_buffer_predisable(struct iio_dev *indio_dev)
>  
>  	pm_runtime_mark_last_busy(dev);
>  	pm_runtime_put_autosuspend(dev);
> +}
> +
> +static int stm32_adc_buffer_predisable(struct iio_dev *indio_dev)
> +{
> +	int ret;
> +
> +	__stm32_adc_buffer_predisable(indio_dev);
> +
> +	ret = iio_triggered_buffer_predisable(indio_dev);
> +	if (ret < 0)
> +		dev_err(&indio_dev->dev, "predisable failed\n");
>  
>  	return ret;
>  }
> @@ -2013,6 +2027,40 @@ static int stm32_adc_remove(struct platform_device *pdev)
>  	return 0;
>  }
>  
> +#if defined(CONFIG_PM_SLEEP)
> +static int stm32_adc_suspend(struct device *dev)
> +{
> +	struct stm32_adc *adc = dev_get_drvdata(dev);
> +	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
> +
> +	if (iio_buffer_enabled(indio_dev))
> +		__stm32_adc_buffer_predisable(indio_dev);
> +
> +	return pm_runtime_force_suspend(dev);
> +}
> +
> +static int stm32_adc_resume(struct device *dev)
> +{
> +	struct stm32_adc *adc = dev_get_drvdata(dev);
> +	struct iio_dev *indio_dev = iio_priv_to_dev(adc);
> +	int ret;
> +
> +	ret = pm_runtime_force_resume(dev);
> +	if (ret < 0)
> +		return ret;
> +
> +	if (!iio_buffer_enabled(indio_dev))
> +		return 0;
> +
> +	ret = stm32_adc_update_scan_mode(indio_dev,
> +					 indio_dev->active_scan_mask);
> +	if (ret < 0)
> +		return ret;
> +
> +	return __stm32_adc_buffer_postenable(indio_dev);
> +}
> +#endif
> +
>  #if defined(CONFIG_PM)
>  static int stm32_adc_runtime_suspend(struct device *dev)
>  {
> @@ -2026,8 +2074,7 @@ static int stm32_adc_runtime_resume(struct device *dev)
>  #endif
>  
>  static const struct dev_pm_ops stm32_adc_pm_ops = {
> -	SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
> -				pm_runtime_force_resume)
> +	SET_SYSTEM_SLEEP_PM_OPS(stm32_adc_suspend, stm32_adc_resume)
>  	SET_RUNTIME_PM_OPS(stm32_adc_runtime_suspend, stm32_adc_runtime_resume,
>  			   NULL)
>  };