From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jonathan Cameron Subject: Re: [PATCH] iio: adc: ti-ads7950: add GPIO support Date: Mon, 11 Feb 2019 20:05:57 +0000 Message-ID: <20190211200557.7648d447@archlinux> References: <1549653856-47409-1-git-send-email-justinpopo6@gmail.com> <20190209170042.69a78684@archlinux> <2e692086-4be5-10ea-34b0-4444995c4275@lechnology.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <2e692086-4be5-10ea-34b0-4444995c4275@lechnology.com> Sender: linux-kernel-owner@vger.kernel.org To: David Lechner 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 List-Id: linux-gpio@vger.kernel.org On Sat, 9 Feb 2019 12:56:11 -0600 David Lechner 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