linux-kernel - Re: [PATCH v2 2/2] iio: adc: at91: fix wrong channel number in triggered buffer mode

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Date:   Tue, 25 Sep 2018 15:17:57 +0200
From:   Ludovic Desroches <ludovic.desroches@...rochip.com>
To:     Eugen Hristev <eugen.hristev@...rochip.com>
CC:     <jic23@...nel.org>, <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <linux-iio@...r.kernel.org>,
        <nicolas.ferre@...rochip.com>,
        Maxime Ripard <maxime.ripard@...tlin.com>
Subject: Re: [PATCH v2 2/2] iio: adc: at91: fix wrong channel number in
 triggered buffer mode

On Mon, Sep 24, 2018 at 10:51:44AM +0300, Eugen Hristev wrote:
> When channels are registered, the hardware channel number is not the
> actual iio channel number.
> This is because the driver is probed with a certain number of accessible
> channels. Some pins are routed and some not, depending on the description of
> the board in the DT.
> Because of that, channels 0,1,2,3 can correspond to hardware channels
> 2,3,4,5 for example.
> In the buffered triggered case, we need to do the translation accordingly.
> Fixed the channel number to stop reading the wrong channel.
> 
> Fixes 0e589d5fb "ARM: AT91: IIO: Add AT91 ADC driver."
> Cc: Maxime Ripard <maxime.ripard@...tlin.com>
> Signed-off-by: Eugen Hristev <eugen.hristev@...rochip.com>
Acked-by: Ludovic Desroches <ludovic.desroches@...rochip.com>

> ---
> Changes in v2:
> - Added 'const' spec to the declaration to avoid build warning
> 
>  drivers/iio/adc/at91_adc.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/adc/at91_adc.c b/drivers/iio/adc/at91_adc.c
> index e3be88e..75d2f73 100644
> --- a/drivers/iio/adc/at91_adc.c
> +++ b/drivers/iio/adc/at91_adc.c
> @@ -248,12 +248,14 @@ static irqreturn_t at91_adc_trigger_handler(int irq, void *p)
>  	struct iio_poll_func *pf = p;
>  	struct iio_dev *idev = pf->indio_dev;
>  	struct at91_adc_state *st = iio_priv(idev);
> +	struct iio_chan_spec const *chan;
>  	int i, j = 0;
>  
>  	for (i = 0; i < idev->masklength; i++) {
>  		if (!test_bit(i, idev->active_scan_mask))
>  			continue;
> -		st->buffer[j] = at91_adc_readl(st, AT91_ADC_CHAN(st, i));
> +		chan = idev->channels + i;
> +		st->buffer[j] = at91_adc_readl(st, AT91_ADC_CHAN(st, chan->channel));
>  		j++;
>  	}
>  
> -- 
> 2.7.4
>