From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1293B8BEC; Sat, 8 Mar 2025 13:24:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741440270; cv=none; b=asbyxf2fMIJQOPn6/d+q7kOZEavs/370PSD0uVF0Cwhf59lWEa/lYneK1MFW+Poi4lNfXtS6Q3ssG9TrdSRS1rYuuECUUvbMXbeFDS2vDNhrkXRvRRquOGn/JGdKtyGLI0/4qmqjaP4crlZt47+XtwUBG70Vk/b9V8Pqytsbnao= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741440270; c=relaxed/simple; bh=dTDm8xkg7Q7HNIkbBzs2xatMRchzur0EuNZ+RwR/AgA=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=W/g7sQsDxqWRwR4kpY/QkVJ6DgGeJwCKAT5XkG2dvXKAtXWU9K9RhOVOPwXM+F1XZvodtvXh9AJzJOVcJfjliTjwPYGIJRYnbJUC+018oyXWhjIcrfWzx+ILlYBnUwnXVI3Z9GpRBlWYH+sNyBWw62CcZxSvcYXs0U3PoW/7OGg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Jb5zoLXO; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Jb5zoLXO" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 48511C4CEE0; Sat, 8 Mar 2025 13:24:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1741440269; bh=dTDm8xkg7Q7HNIkbBzs2xatMRchzur0EuNZ+RwR/AgA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=Jb5zoLXOcy/mkzD8h2ln0JZtm1mshMY+y/G9y7BNUBtYTt4XpdhKOZH1o4S+Cb8WF Sh1KRrHFlYOsVmfQxKQeJvlHl1y1LSyPmklJhKkllC+H0gOfwlt9EK/ZsSnuV/QfsL wfH2Ll9xBqJXTdcUvhDi4BFkFsm7As32OZpSNX9XUkA+N127AF07CMVzDDvoNTv7S5 cGohVy7X3mXIExEX0XiLWf3DotLjInjdb9cRwBuyPpJTl7aOgW9TfpjGVVYZJSuJ4S RrsMRxJBr4iKefYPosxjFrwd6d6EuLHZu6AYUuTyDuvFQBzXPlttjymxNOcqVAmTpe I/mVrBOKSa3Ug== Date: Sat, 8 Mar 2025 13:24:20 +0000 From: Jonathan Cameron To: Jonathan Santos Cc: , , , , , , , , , , , , , , , , Subject: Re: [PATCH v4 07/17] iio: adc: ad7768-1: remove unnecessary locking Message-ID: <20250308132420.29d8dc90@jic23-huawei> In-Reply-To: References: X-Mailer: Claws Mail 4.3.0 (GTK 3.24.48; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Thu, 6 Mar 2025 18:01:51 -0300 Jonathan Santos wrote: > The current locking is only preventing a triggered buffer Transfer and a > debugfs register access from happening at the same time. If a register > access happens during a buffered read, the action is doomed to fail anyway, > since we need to write a magic value to exit continuous read mode. > > Remove locking from the trigger handler and use > iio_device_claim_direct_mode() instead in the register access function. > > Reviewed-by: David Lechner > Signed-off-by: Jonathan Santos I don't really want more of the old school direct_mode calls so I applied this with following tweak. Please take a look at the result on testing branch of iio.git. diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c index a427427aa324..5a863005aca6 100644 --- a/drivers/iio/adc/ad7768-1.c +++ b/drivers/iio/adc/ad7768-1.c @@ -255,9 +255,8 @@ static int ad7768_reg_access(struct iio_dev *indio_dev, struct ad7768_state *st = iio_priv(indio_dev); int ret; - ret = iio_device_claim_direct_mode(indio_dev); - if (ret) - return ret; + if (!iio_device_claim_direct(indio_dev)) + return -EBUSY; if (readval) { ret = ad7768_spi_reg_read(st, reg, 1); @@ -269,7 +268,7 @@ static int ad7768_reg_access(struct iio_dev *indio_dev, ret = ad7768_spi_reg_write(st, reg, writeval); } err_release: - iio_device_release_direct_mode(indio_dev); + iio_device_release_direct(indio_dev); return ret; } > --- > v4 Changes: > * None. > > v3 Changes: > * Also removed the mutex_init and lock variable. > > v2 Changes: > * New patch in v2. It replaces the guard(mutex) patch. > --- > drivers/iio/adc/ad7768-1.c | 21 +++++++++------------ > 1 file changed, 9 insertions(+), 12 deletions(-) > > diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c > index 2e2d50ccb744..f5509a0a36ab 100644 > --- a/drivers/iio/adc/ad7768-1.c > +++ b/drivers/iio/adc/ad7768-1.c > @@ -154,7 +154,6 @@ static const struct iio_chan_spec ad7768_channels[] = { > struct ad7768_state { > struct spi_device *spi; > struct regulator *vref; > - struct mutex lock; > struct clk *mclk; > unsigned int mclk_freq; > unsigned int samp_freq; > @@ -256,18 +255,21 @@ static int ad7768_reg_access(struct iio_dev *indio_dev, > struct ad7768_state *st = iio_priv(indio_dev); > int ret; > > - mutex_lock(&st->lock); > + ret = iio_device_claim_direct_mode(indio_dev); > + if (ret) > + return ret; > + > if (readval) { > ret = ad7768_spi_reg_read(st, reg, 1); > if (ret < 0) > - goto err_unlock; > + goto err_release; > *readval = ret; > ret = 0; > } else { > ret = ad7768_spi_reg_write(st, reg, writeval); > } > -err_unlock: > - mutex_unlock(&st->lock); > +err_release: > + iio_device_release_direct_mode(indio_dev); > > return ret; > } > @@ -471,18 +473,15 @@ static irqreturn_t ad7768_trigger_handler(int irq, void *p) > struct ad7768_state *st = iio_priv(indio_dev); > int ret; > > - mutex_lock(&st->lock); > - > ret = spi_read(st->spi, &st->data.scan.chan, 3); > if (ret < 0) > - goto err_unlock; > + goto out; > > iio_push_to_buffers_with_timestamp(indio_dev, &st->data.scan, > iio_get_time_ns(indio_dev)); > > -err_unlock: > +out: > iio_trigger_notify_done(indio_dev->trig); > - mutex_unlock(&st->lock); > > return IRQ_HANDLED; > } > @@ -611,8 +610,6 @@ static int ad7768_probe(struct spi_device *spi) > > st->mclk_freq = clk_get_rate(st->mclk); > > - mutex_init(&st->lock); > - > indio_dev->channels = ad7768_channels; > indio_dev->num_channels = ARRAY_SIZE(ad7768_channels); > indio_dev->name = spi_get_device_id(spi)->name;