Commit 6a882a2c authored by Heiner Kallweit's avatar Heiner Kallweit Committed by Jonathan Cameron
Browse files

iio: adc: meson-saradc: improve meson_sar_adc_read_raw_sample 



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: default avatarHeiner Kallweit <hkallweit1@gmail.com>
Acked-by: default avatarMartin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: default avatarJonathan Cameron <jic23@kernel.org>
parent 3af10913

drivers/iio/adc/meson_saradc.c

+17 −19
Original line number Diff line number Diff line
@@ -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;



	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, &regval);



		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 element(s) instead of one\n", count);

		return -EINVAL;

	}



	if (!count)

		return -ENOENT;

	regmap_read(priv->regmap, MESON_SAR_ADC_FIFO_RD, &regval);

	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);

	*val = fifo_val;



	return 0;

}

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