Re: [PATCH 2/7] iio: adc: ad7791: claim direct mode when writing frequency

From	Lars-Peter Clausen <lars@metafoo.de>
Newsgroups	linux.kernel
Subject	Re: [PATCH 2/7] iio: adc: ad7791: claim direct mode when writing frequency
Date	2016-05-31 15:30 +0200
Message-ID	<rERU6-3h1-7@gated-at.bofh.it> (permalink)
References	<rCq1X-7jq-3@gated-at.bofh.it> <rCq1X-7jq-1@gated-at.bofh.it> <rCEoi-8jG-17@gated-at.bofh.it> <rEcnU-Fq-3@gated-at.bofh.it>
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On 05/29/2016 07:06 PM, Jonathan Cameron wrote:
> 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.

It will only be locked once. sysfs_streq() will only match for a single
item. But you are right the code could be refactored to make that more
clearer. First run the lookup look and then apply afterwards.

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[PATCH 2/7] iio: adc: ad7791: claim direct mode when writing  frequency Alison Schofield <amsfield22@gmail.com> - 2016-05-24 21:20 +0200
  Re: [PATCH 2/7] iio: adc: ad7791: claim direct mode when writing frequency Daniel Baluta <daniel.baluta@gmail.com> - 2016-05-25 12:40 +0200
    Re: [PATCH 2/7] iio: adc: ad7791: claim direct mode when writing  frequency Jonathan Cameron <jic23@kernel.org> - 2016-05-29 19:10 +0200
      Re: [PATCH 2/7] iio: adc: ad7791: claim direct mode when writing  frequency Jonathan Cameron <jic23@kernel.org> - 2016-05-29 19:10 +0200
      Re: [PATCH 2/7] iio: adc: ad7791: claim direct mode when writing  frequency Lars-Peter Clausen <lars@metafoo.de> - 2016-05-31 15:30 +0200

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