From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from saturn.retrosnub.co.uk ([178.18.118.26]:33682 "EHLO saturn.retrosnub.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752862AbcE2RHo (ORCPT ); Sun, 29 May 2016 13:07:44 -0400 Subject: Re: [PATCH 2/7] iio: adc: ad7791: claim direct mode when writing frequency To: Daniel Baluta , Alison Schofield References: Cc: Lars-Peter Clausen , "Hennerich, Michael" , Hartmut Knaack , Peter Meerwald-Stadler , "linux-iio@vger.kernel.org" , Linux Kernel Mailing List From: Jonathan Cameron Message-ID: Date: Sun, 29 May 2016 18:07:41 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Sender: linux-iio-owner@vger.kernel.org List-Id: linux-iio@vger.kernel.org On 29/05/16 18:06, Jonathan Cameron wrote: > On 25/05/16 11:34, Daniel Baluta wrote: >> On Tue, May 24, 2016 at 10:16 PM, Alison Schofield 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 >>> Cc: Daniel Baluta >> >> Looks good to me. We could use an Acked-by from Lars here. >> >> Acked-by: Daniel Baluta > 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. > > Can apply such a change at a later date however. > > Applied to the togreg branch of iio.git - initially pushed out as testing > for the autobuilders to play with it. Actually haven't seen Daniel suggesting an Ack from Lars might be good for this one I've backed it out for now. Lars? > > Thanks, > > Jonathan > >> >>> --- >>> drivers/iio/adc/ad7791.c | 15 ++++----------- >>> 1 file changed, 4 insertions(+), 11 deletions(-) >>> >>> diff --git a/drivers/iio/adc/ad7791.c b/drivers/iio/adc/ad7791.c >>> index cf172d58..f7edacc 100644 >>> --- a/drivers/iio/adc/ad7791.c >>> +++ b/drivers/iio/adc/ad7791.c >>> @@ -272,24 +272,17 @@ static ssize_t ad7791_write_frequency(struct device *dev, >>> struct ad7791_state *st = iio_priv(indio_dev); >>> int i, ret; >>> >>> - mutex_lock(&indio_dev->mlock); >>> - if (iio_buffer_enabled(indio_dev)) { >>> - mutex_unlock(&indio_dev->mlock); >>> - return -EBUSY; >>> - } >>> - mutex_unlock(&indio_dev->mlock); >>> - >>> - ret = -EINVAL; >>> - >>> for (i = 0; i < ARRAY_SIZE(ad7791_sample_freq_avail); i++) { >>> if (sysfs_streq(ad7791_sample_freq_avail[i], buf)) { >>> >>> - mutex_lock(&indio_dev->mlock); >>> + ret = iio_device_claim_direct_mode(indio_dev); >>> + if (ret) >>> + return ret; >>> st->filter &= ~AD7791_FILTER_RATE_MASK; >>> st->filter |= i; >>> ad_sd_write_reg(&st->sd, AD7791_REG_FILTER, >>> sizeof(st->filter), st->filter); >>> - mutex_unlock(&indio_dev->mlock); >>> + iio_device_release_direct_mode(indio_dev); >>> ret = 0; >>> break; >>> } >>> -- >>> 2.1.4 >>> >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-iio" in >>> the body of a message to majordomo@vger.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html > > -- > To unsubscribe from this list: send the line "unsubscribe linux-iio" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >