linux-kernel - Re: [PATCH v2 2/2] iio: at91-sama5d2_adc: adjust iio_triggered_buffer

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Date:   Sun, 19 Apr 2020 12:04:01 +0200
From:   ludovic.desroches@...rochip.com
To:     Alexandru Ardelean <alexandru.ardelean@...log.com>
Cc:     linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        jic23@...nel.org, eugen.hristev@...rochip.com
Subject: Re: [PATCH v2 2/2] iio: at91-sama5d2_adc: adjust
 iio_triggered_buffer_{predisable,postenable} positions

On Wed, Mar 04, 2020 at 10:42:19AM +0200, Alexandru Ardelean wrote:
> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> 
> The iio_triggered_buffer_{predisable,postenable} functions attach/detach
> poll functions.
> 
> In most cases the iio_triggered_buffer_postenable() should be called first
> to attach the poll function, and then the driver can init the data to be
> triggered.
> In this case it's the other way around: the DMA code should be initialized
> before the attaching the poll function and the reverse should be done when
> un-initializing.
> 
> To make things easier when removing the iio_triggered_buffer_postenable() &
> iio_triggered_buffer_predisable() functions from the IIO core API, the DMA
> code has been moved into preenable() for init, and postdisable() for
> uninit.
> 
> Signed-off-by: Alexandru Ardelean <alexandru.ardelean@...log.com>

Reviewed-by: Ludovic Desroches <ludovic.desroches@...rochip.com>

> ---
>  drivers/iio/adc/at91-sama5d2_adc.c | 32 ++++++++++++++++++++----------
>  1 file changed, 22 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/iio/adc/at91-sama5d2_adc.c b/drivers/iio/adc/at91-sama5d2_adc.c
> index f2a74c47c768..2e01073d401d 100644
> --- a/drivers/iio/adc/at91-sama5d2_adc.c
> +++ b/drivers/iio/adc/at91-sama5d2_adc.c
> @@ -882,7 +882,7 @@ static bool at91_adc_current_chan_is_touch(struct iio_dev *indio_dev)
>                                AT91_SAMA5D2_MAX_CHAN_IDX + 1);
>  }
> 
> -static int at91_adc_buffer_postenable(struct iio_dev *indio_dev)
> +static int at91_adc_buffer_preenable(struct iio_dev *indio_dev)
>  {
>         int ret;
>         struct at91_adc_state *st = iio_priv(indio_dev);
> @@ -902,13 +902,20 @@ static int at91_adc_buffer_postenable(struct iio_dev *indio_dev)
>                 return ret;
>         }
> 
> +       return 0;
> +}
> +
> +static int at91_adc_buffer_postenable(struct iio_dev *indio_dev)
> +{
> +       if (at91_adc_current_chan_is_touch(indio_dev))
> +               return 0;
> +
>         return iio_triggered_buffer_postenable(indio_dev);
>  }
> 
> -static int at91_adc_buffer_predisable(struct iio_dev *indio_dev)
> +static int at91_adc_buffer_postdisable(struct iio_dev *indio_dev)
>  {
>         struct at91_adc_state *st = iio_priv(indio_dev);
> -       int ret;
>         u8 bit;
> 
>         /* check if we are disabling triggered buffer or the touchscreen */
> @@ -919,13 +926,8 @@ static int at91_adc_buffer_predisable(struct iio_dev *indio_dev)
>         if (!(indio_dev->currentmode & INDIO_ALL_TRIGGERED_MODES))
>                 return -EINVAL;
> 
> -       /* continue with the triggered buffer */
> -       ret = iio_triggered_buffer_predisable(indio_dev);
> -       if (ret < 0)
> -               dev_err(&indio_dev->dev, "buffer predisable failed\n");
> -
>         if (!st->dma_st.dma_chan)
> -               return ret;
> +               return 0;
> 
>         /* if we are using DMA we must clear registers and end DMA */
>         dmaengine_terminate_sync(st->dma_st.dma_chan);
> @@ -952,10 +954,20 @@ static int at91_adc_buffer_predisable(struct iio_dev *indio_dev)
> 
>         /* read overflow register to clear possible overflow status */
>         at91_adc_readl(st, AT91_SAMA5D2_OVER);
> -       return ret;
> +       return 0;
> +}
> +
> +static int at91_adc_buffer_predisable(struct iio_dev *indio_dev)
> +{
> +       if (at91_adc_current_chan_is_touch(indio_dev))
> +               return 0;
> +
> +       return iio_triggered_buffer_predisable(indio_dev);
>  }
> 
>  static const struct iio_buffer_setup_ops at91_buffer_setup_ops = {
> +       .preenable = &at91_adc_buffer_preenable,
> +       .postdisable = &at91_adc_buffer_postdisable,
>         .postenable = &at91_adc_buffer_postenable,
>         .predisable = &at91_adc_buffer_predisable,
>  };
> --
> 2.20.1
>