From: Jonathan Cameron <jic23@kernel.org>
To: David Lechner <david@lechnology.com>
Cc: justinpopo6@gmail.com, linux-iio@vger.kernel.org,
linux-gpio@vger.kernel.org,
bcm-kernel-feedback-list@broadcom.com, f.fainelli@gmail.com,
bgolaszewski@baylibre.com, linus.walleij@linaro.org,
knaack.h@gmx.de, lars@metafoo.de, pmeerw@pmeerw.net,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] iio: adc: ti-ads7950: add GPIO support
Date: Mon, 11 Feb 2019 20:05:57 +0000 [thread overview]
Message-ID: <20190211200557.7648d447@archlinux> (raw)
In-Reply-To: <2e692086-4be5-10ea-34b0-4444995c4275@lechnology.com>
On Sat, 9 Feb 2019 12:56:11 -0600
David Lechner <david@lechnology.com> wrote:
> On 2/9/19 11:00 AM, Jonathan Cameron wrote:
> > Nope. This is a state lock used to protect against transitions between
> > different modes of the IIO device (buffered vs polled), it
> > isn't suitable for general use.
> >
> > The driver should be modified to handle that correctly.
> > We have iio_claim_direct_mode etc that deal with the case
> > where a device can't do certain operations whilst in buffered
> > mode. Note it can fail and should.
> >
> > Seems there are more drivers still doing this than I thought.
> > If anyone is bored and wants to clean them out, that would be
> > most appreciated!
> >
> > If you need locking to protect a local buffer or the device
> > state, define a new lock to do it with clearly documented
> > scope.
>
> Just as a reminder, there is a use case for this particular
> chip that requires buffered mode and direct mode at the same
> time.
>
> https://patchwork.kernel.org/patch/10539021/
> https://patchwork.kernel.org/patch/10527757/
Thanks, I had indeed forgotten that entirely.
So it should have a local lock and not take mlock explicitly at all.
Jonathan
next prev parent reply other threads:[~2019-02-11 20:06 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-08 19:24 [PATCH] iio: adc: ti-ads7950: add GPIO support justinpopo6
2019-02-09 17:00 ` Jonathan Cameron
2019-02-09 18:56 ` David Lechner
2019-02-11 20:05 ` Jonathan Cameron [this message]
2019-02-11 20:17 ` Justin Chen
2019-02-12 20:35 ` Jonathan Cameron
2019-02-11 8:34 ` Linus Walleij
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