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SubjectRe: [PATCH 3/3] iio: adc: stm32-adc: switch off running adc when going to low power
On Tue, 20 Nov 2018 11:12:32 +0100
Fabrice Gasnier <fabrice.gasnier@st.com> 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 <fabrice.gasnier@st.com>
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)
> };

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