From: Jonathan Cameron <jic23@kernel.org>
To: Sven Van Asbroeck <thesven73@gmail.com>
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
Subject: Re: [PATCH v2 1/3] iio: light: Add driver for ap3216c
Date: Sat, 9 Mar 2019 17:33:46 +0000 [thread overview]
Message-ID: <20190309173346.2a1ea4f8@archlinux> (raw)
In-Reply-To: <CAGngYiW0Sf1mg-F18p_NeJZUMsvvceRn4HvNXAkdLaS9AfFDMQ@mail.gmail.com>
On Mon, 4 Mar 2019 11:25:01 -0500
Sven Van Asbroeck <thesven73@gmail.com> wrote:
> On Sun, Mar 3, 2019 at 9:38 AM Jonathan Cameron <jic23@kernel.org> wrote:
> >
> > Hmm. Just been thinking a bit about the events on here and wondered
> > if it is possible to mask them through careful use of the threshold
> > values - i.e. can we stop the hardware generating the interrupts for
> > the ones we don't want. It would be unusual for hardware to be
> > designed where this wasn't possible.
>
> Excellent point! People with power / battery constraints take a dim view of
> receiving interrupts when no-one wants them. So disabling them in h/w
> is definitely the way to go, if possible.
>
> And yes, this also makes a non-issue of thresh_en visibility concerns, if any.
>
> >
> > Alternatively if you have a scope or equivalent to verify if it is doing
> > these as a multi byte read and working that would be even better.
> > It is not uncommon for hardware to implement fairly standard i2c features
> > like this and not document them because they weren't what the test code
> > the docs writer got given does! (may not be true here of course)
>
> Or alternatively, the current chip rev supports undocumented multi-reads,
> and the next revision silently drops support, thereby breaking the driver...
> Been there, done that, got the T-shirt :(
Indeed it's a risk. Sadly hardware guys never have a 'we mustn't break
software' rule like we do for userspace!
Jonathan
prev parent reply other threads:[~2019-03-09 17:33 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-24 20:34 [PATCH v2 1/3] iio: light: Add driver for ap3216c Robert Eshleman
2019-02-24 20:33 ` [PATCH v2 2/3] dt-bindings: vendor-prefix: add prefix for Lite-On Corp Robert Eshleman
2019-02-26 22:40 ` Rob Herring
2019-02-24 20:33 ` [PATCH v2 3/3] dt-bindings: iio: light: Add ap3216c Robert Eshleman
2019-02-26 22:41 ` Rob Herring
2019-02-27 20:40 ` [PATCH v2 1/3] iio: light: Add driver for ap3216c Tomasz Duszynski
2019-02-28 16:49 ` Sven Van Asbroeck
2019-03-03 14:38 ` Jonathan Cameron
2019-03-04 16:25 ` Sven Van Asbroeck
2019-03-09 17:33 ` Jonathan Cameron [this message]
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