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 <amsfiel...@gmail.com> Cc: Daniel Baluta <daniel.bal...@gmail.com> --- Changes in v2 Refactored function per reviewers comments Updated changelog drivers/iio/adc/ad7791.c | 36 ++++++++++++++---------------------- 1 file changed, 14 insertions(+), 22 deletions(-) diff --git a/drivers/iio/adc/ad7791.c b/drivers/iio/adc/ad7791.c index cf172d58..1dfe641 100644 --- a/drivers/iio/adc/ad7791.c +++ b/drivers/iio/adc/ad7791.c @@ -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; + + 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 ret ? ret : len; + return len; } static IIO_DEV_ATTR_SAMP_FREQ(S_IWUSR | S_IRUGO, -- 2.1.4