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iio: adc: ad7793: 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>
hifive-unleashed-5.1
Alison Schofield 2016-06-01 21:28:14 -07:00 committed by Jonathan Cameron
parent 7c7e9dad70
commit afa814841c
1 changed files with 13 additions and 19 deletions
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32
drivers/iio/adc/ad7793.c
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@ -369,13 +369,6 @@ static ssize_t ad7793_write_frequency(struct device *dev,
long lval;
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 = kstrtol(buf, 10, &lval);
if (ret)
return ret;
@ -383,20 +376,21 @@ static ssize_t ad7793_write_frequency(struct device *dev,
if (lval == 0)
return -EINVAL;
ret = -EINVAL;
for (i = 0; i < 16; i++)
if (lval == st->chip_info->sample_freq_avail[i]) {
mutex_lock(&indio_dev->mlock);
st->mode &= ~AD7793_MODE_RATE(-1);
st->mode |= AD7793_MODE_RATE(i);
ad_sd_write_reg(&st->sd, AD7793_REG_MODE,
sizeof(st->mode), st->mode);
mutex_unlock(&indio_dev->mlock);
ret = 0;
}
if (lval == st->chip_info->sample_freq_avail[i])
break;
if (i == 16)
return -EINVAL;
return ret ? ret : len;
ret = iio_device_claim_direct_mode(indio_dev);
if (ret)
return ret;
st->mode &= ~AD7793_MODE_RATE(-1);
st->mode |= AD7793_MODE_RATE(i);
ad_sd_write_reg(&st->sd, AD7793_REG_MODE, sizeof(st->mode), st->mode);
iio_device_release_direct_mode(indio_dev);
return len;
}
static IIO_DEV_ATTR_SAMP_FREQ(S_IWUSR | S_IRUGO,