From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752877AbcE2RGX (ORCPT ); Sun, 29 May 2016 13:06:23 -0400 Received: from saturn.retrosnub.co.uk ([178.18.118.26]:33669 "EHLO saturn.retrosnub.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752725AbcE2RGU (ORCPT ); Sun, 29 May 2016 13:06:20 -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 18:06:18 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. 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