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iio: adc: ad7791: claim direct mode when writing frequency 

Driver was checking for direct mode and trying to lock it, but
left a gap where mode could change before the desired operation.
Use iio_device_claim_direct_mode() to guarantee device stays in
direct mode.

Refactor function to clarify look-up followed by lock sequence.

Signed-off-by: Alison Schofield <amsfield22@gmail.com>
Cc: Daniel Baluta <daniel.baluta@gmail.com>
Acked-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This commit is contained in:
Alison Schofield 2016-05-31 21:35:49 -07:00 committed by Jonathan Cameron
parent afa814841c
commit d7203ad864
1 changed files with 14 additions and 22 deletions
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36
drivers/iio/adc/ad7791.c
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@ -272,30 +272,22 @@ static ssize_t ad7791_write_frequency(struct device *dev,
struct ad7791_state *st = iio_priv(indio_dev);
int i, ret;
mutex_lock(&indio_dev->mlock);
if (iio_buffer_enabled(indio_dev)) {
mutex_unlock(&indio_dev->mlock);
return -EBUSY;
}
mutex_unlock(&indio_dev->mlock);
ret = -EINVAL;
for (i = 0; i < ARRAY_SIZE(ad7791_sample_freq_avail); i++) {
if (sysfs_streq(ad7791_sample_freq_avail[i], buf)) {
mutex_lock(&indio_dev->mlock);
st->filter &= ~AD7791_FILTER_RATE_MASK;
st->filter |= i;
ad_sd_write_reg(&st->sd, AD7791_REG_FILTER,
sizeof(st->filter), st->filter);
mutex_unlock(&indio_dev->mlock);
ret = 0;
for (i = 0; i < ARRAY_SIZE(ad7791_sample_freq_avail); i++)
if (sysfs_streq(ad7791_sample_freq_avail[i], buf))
break;
}
}
if (i == ARRAY_SIZE(ad7791_sample_freq_avail))
return -EINVAL;
return ret ? ret : len;
ret = iio_device_claim_direct_mode(indio_dev);
if (ret)
return ret;
st->filter &= ~AD7791_FILTER_RATE_MASK;
st->filter |= i;
ad_sd_write_reg(&st->sd, AD7791_REG_FILTER, sizeof(st->filter),
st->filter);
iio_device_release_direct_mode(indio_dev);
return len;
}
static IIO_DEV_ATTR_SAMP_FREQ(S_IWUSR | S_IRUGO,