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SubjectRe: [PATCH 2/7] iio: adc: ad7791: claim direct mode when writing frequency
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On 25/05/16 11:34, Daniel Baluta wrote:
> On Tue, May 24, 2016 at 10:16 PM, Alison Schofield <amsfield22@gmail.com> wrote:
>> 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.
>>
>> Signed-off-by: Alison Schofield <amsfield22@gmail.com>
>> Cc: Daniel Baluta <daniel.baluta@gmail.com>
>
> Looks good to me. We could use an Acked-by from Lars here.
>
> Acked-by: Daniel Baluta <daniel.baluta@gmail.com>
This one is a little more interesting. I wonder if we wouldn't be better
off taking the lock for the whole function rather than dropping it for
short periods.

Can apply such a change at a later date however.

Applied to the togreg branch of iio.git - initially pushed out as testing
for the autobuilders to play with it.

Thanks,

Jonathan

>
>> ---
>> drivers/iio/adc/ad7791.c | 15 ++++-----------
>> 1 file changed, 4 insertions(+), 11 deletions(-)
>>
>> diff --git a/drivers/iio/adc/ad7791.c b/drivers/iio/adc/ad7791.c
>> index cf172d58..f7edacc 100644
>> --- a/drivers/iio/adc/ad7791.c
>> +++ b/drivers/iio/adc/ad7791.c
>> @@ -272,24 +272,17 @@ 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);
>> + 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);
>> - mutex_unlock(&indio_dev->mlock);
>> + iio_device_release_direct_mode(indio_dev);
>> ret = 0;
>> break;
>> }
>> --
>> 2.1.4
>>
>> --
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