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

From: Jonathan Cameron
Date: Mon Sep 24 2018 - 16:25:49 EST


On Mon, 24 Sep 2018 10:51:44 +0300
Eugen Hristev <eugen.hristev@xxxxxxxxxxxxx> 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@xxxxxxxxxxx>
> Signed-off-by: Eugen Hristev <eugen.hristev@xxxxxxxxxxxxx>
Again. Looks entirely sensible to me, but I'd like to leave it
a little longer for Maxime to have an opportunity to comment.
(or anyone else for that matter!)

Do give me a poke if I seem to have forgotten this in a week or so
though.

Thanks,

Jonathan

> ---
> 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++;
> }
>