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From:   Sven Van Asbroeck <thesven73@gmail.com>
Date:   Tue, 12 Feb 2019 23:56:19 -0500
Message-ID: <CAGngYiVDOTaqD3p4ZskdM0RjUZUqubXR6KsDOcVMEO5mBi2rBQ@mail.gmail.com>
Subject: Re: [PATCH 1/3] iio: light: Add driver for ap3216c
To:     Jonathan Cameron <jic23@kernel.org>
Cc:     Robert Eshleman <bobbyeshleman@gmail.com>,
        Hartmut Knaack <knaack.h@gmx.de>,
        Lars-Peter Clausen <lars@metafoo.de>,
        Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-iio@vger.kernel.org
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On Tue, Feb 12, 2019 at 11:40 PM Sven Van Asbroeck <thesven73@gmail.com> wrote:
>
> Next, read ALS and PS _exclusively_ in the irq handler, guard it with
> a mutex:
>

Wait a second, that wouldn't work, because we don't get an interrupt
on every ALS/PS
conversion, correct ?

In that case, don't cache the als/ps value in the irq handler, but
read it from the hardware in
ap3216c_read_raw, while holding the mutex.

That would still guard against:
- _LO and _HI getting interleaved
- userspace reading the value in between sending the event, and
clearing the int bit
- the int handler not immediately seeing _thresh_en

Apologies for the confusion :)