On Tue, Feb 14, 2017 at 10:58 PM, Heiner Kallweit <hkallweit1@xxxxxxxxx> wrote:
> After sampling there should always be only one value in the FIFO.
> This also applies to averaging mode as the averaging is done
> chip-internally. So we don't have to loop and let the driver
> complain if there's not exactly one value in the FIFO.
>
> If the value belongs to a different channel then don't silently
> swallow the value but complain.
>
> Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
Acked-by: Martin Blumenstingl <martin.blumenstingl@xxxxxxxxxxxxxx>
> ---
> drivers/iio/adc/meson_saradc.c | 36 +++++++++++++++++-------------------
> 1 file changed, 17 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/iio/adc/meson_saradc.c b/drivers/iio/adc/meson_saradc.c
> index dbd56bcc..d39711c0 100644
> --- a/drivers/iio/adc/meson_saradc.c
> +++ b/drivers/iio/adc/meson_saradc.c
> @@ -278,33 +278,31 @@ static int meson_sar_adc_read_raw_sample(struct iio_dev *indio_dev,
> int *val)
> {
> struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
> - int regval, fifo_chan, fifo_val, sum = 0, count = 0;
> + int regval, fifo_chan, fifo_val, count;
>
> if(!wait_for_completion_timeout(&priv->done,
> msecs_to_jiffies(MESON_SAR_ADC_TIMEOUT)))
> return -ETIMEDOUT;
>
I thought I had changed the following loop when I introduced
meson_sar_adc_clear_fifo() but it seems that I didn't do it - so
thanks for cleaning this up!
> - while (meson_sar_adc_get_fifo_count(indio_dev) > 0 &&
> - count < MESON_SAR_ADC_MAX_FIFO_SIZE) {
> - regmap_read(priv->regmap, MESON_SAR_ADC_FIFO_RD, ®val);
> -
> - fifo_chan = FIELD_GET(MESON_SAR_ADC_FIFO_RD_CHAN_ID_MASK,
> - regval);
> - if (fifo_chan != chan->channel)
> - continue;
> -
> - fifo_val = FIELD_GET(MESON_SAR_ADC_FIFO_RD_SAMPLE_VALUE_MASK,
> - regval);
> - fifo_val &= (BIT(priv->data->resolution) - 1);
> -
> - sum += fifo_val;
> - count++;
> + count = meson_sar_adc_get_fifo_count(indio_dev);
> + if (count != 1) {
> + dev_err(&indio_dev->dev,
> + "ADC FIFO has %d elements instead of one\n", count);
> + return -EINVAL;
> }
>
> - if (!count)
> - return -ENOENT;
> + regmap_read(priv->regmap, MESON_SAR_ADC_FIFO_RD, ®val);
> + fifo_chan = FIELD_GET(MESON_SAR_ADC_FIFO_RD_CHAN_ID_MASK, regval);
> + if (fifo_chan != chan->channel) {
> + dev_err(&indio_dev->dev,
> + "ADC FIFO entry belongs to channel %d instead of %d\n",
> + fifo_chan, chan->channel);
> + return -EINVAL;
> + }
>
> - *val = sum / count;
> + fifo_val = FIELD_GET(MESON_SAR_ADC_FIFO_RD_SAMPLE_VALUE_MASK, regval);
> + fifo_val &= GENMASK(priv->data->resolution - 1, 0);
my code used "BIT(priv->data->resolution) - 1" instead of GENMASK. it
shouldn't make a difference so I don't see an issue with that change
> + *val = fifo_val;
>
> return 0;
> }
> --
> 2.11.1
>
>
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