linux-kernel - Re: [PATCH] iio: adc: stm32-adc: dma transfers cleanup

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Message-ID: <8ed73130-57e7-4073-cdf2-5f31596e728c@st.com>
Date:   Thu, 5 Nov 2020 18:38:27 +0100
From:   Fabrice Gasnier <fabrice.gasnier@...com>
To:     Olivier Moysan <olivier.moysan@...com>, <jic23@...nel.org>,
        <knaack.h@....de>, <lars@...afoo.de>, <pmeerw@...erw.net>,
        <alexandre.torgue@...com>
CC:     <linux-iio@...r.kernel.org>,
        <linux-stm32@...md-mailman.stormreply.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] iio: adc: stm32-adc: dma transfers cleanup

On 11/5/20 3:29 PM, Olivier Moysan wrote:
> - Remove processing related to DMA in irq handler as this
> data transfer is managed directly in DMA callback.
> - Update comment in stm32_adc_set_watermark() function.
> 
> Signed-off-by: Olivier Moysan <olivier.moysan@...com>

Hi Olivier,

Reviewed-by: Fabrice Gasnier <fabrice.gasnier@...com>

Thanks,
Fabrice
> ---
>  drivers/iio/adc/stm32-adc.c | 29 ++++++-----------------------
>  1 file changed, 6 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/iio/adc/stm32-adc.c b/drivers/iio/adc/stm32-adc.c
> index b3f31f147347..08be826f1462 100644
> --- a/drivers/iio/adc/stm32-adc.c
> +++ b/drivers/iio/adc/stm32-adc.c
> @@ -1310,7 +1310,7 @@ static int stm32_adc_set_watermark(struct iio_dev *indio_dev, unsigned int val)
>  	 * dma cyclic transfers are used, buffer is split into two periods.
>  	 * There should be :
>  	 * - always one buffer (period) dma is working on
> -	 * - one buffer (period) driver can push with iio_trigger_poll().
> +	 * - one buffer (period) driver can push data.
>  	 */
>  	watermark = min(watermark, val * (unsigned)(sizeof(u16)));
>  	adc->rx_buf_sz = min(rx_buf_sz, watermark * 2 * adc->num_conv);
> @@ -1573,31 +1573,14 @@ static irqreturn_t stm32_adc_trigger_handler(int irq, void *p)
>  
>  	dev_dbg(&indio_dev->dev, "%s bufi=%d\n", __func__, adc->bufi);
>  
> -	if (!adc->dma_chan) {
> -		/* reset buffer index */
> -		adc->bufi = 0;
> -		iio_push_to_buffers_with_timestamp(indio_dev, adc->buffer,
> -						   pf->timestamp);
> -	} else {
> -		int residue = stm32_adc_dma_residue(adc);
> -
> -		while (residue >= indio_dev->scan_bytes) {
> -			u16 *buffer = (u16 *)&adc->rx_buf[adc->bufi];
> -
> -			iio_push_to_buffers_with_timestamp(indio_dev, buffer,
> -							   pf->timestamp);
> -			residue -= indio_dev->scan_bytes;
> -			adc->bufi += indio_dev->scan_bytes;
> -			if (adc->bufi >= adc->rx_buf_sz)
> -				adc->bufi = 0;
> -		}
> -	}
> -
> +	/* reset buffer index */
> +	adc->bufi = 0;
> +	iio_push_to_buffers_with_timestamp(indio_dev, adc->buffer,
> +					   pf->timestamp);
>  	iio_trigger_notify_done(indio_dev->trig);
>  
>  	/* re-enable eoc irq */
> -	if (!adc->dma_chan)
> -		stm32_adc_conv_irq_enable(adc);
> +	stm32_adc_conv_irq_enable(adc);
>  
>  	return IRQ_HANDLED;
>  }
>