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[98.183.112.25]) by smtp.gmail.com with ESMTPSA id 006d021491bc7-5fa8b9b8fd3sm2519790eaf.40.2025.01.27.14.46.17 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 27 Jan 2025 14:46:19 -0800 (PST) Message-ID: Date: Mon, 27 Jan 2025 16:46:17 -0600 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 09/16] iio: adc: ad7768-1: remove unnecessary locking To: Jonathan Santos , linux-iio@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org Cc: lars@metafoo.de, Michael.Hennerich@analog.com, marcelo.schmitt@analog.com, jic23@kernel.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, jonath4nns@gmail.com, marcelo.schmitt1@gmail.com References: From: David Lechner Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 1/27/25 9:13 AM, 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. > > Signed-off-by: Jonathan Santos > --- > v2 Changes: > * New patch in v2. It replaces the guard(mutex) patch. > --- > drivers/iio/adc/ad7768-1.c | 23 ++++++++++------------- > 1 file changed, 10 insertions(+), 13 deletions(-) > > diff --git a/drivers/iio/adc/ad7768-1.c b/drivers/iio/adc/ad7768-1.c > index 17a49bf74637..5e2093be9b92 100644 > --- a/drivers/iio/adc/ad7768-1.c > +++ b/drivers/iio/adc/ad7768-1.c > @@ -271,16 +271,16 @@ static int ad7768_reg_access(struct iio_dev *indio_dev, > struct ad7768_state *st = iio_priv(indio_dev); > int ret; > > - mutex_lock(&st->lock); > - if (readval) { > + ret = iio_device_claim_direct_mode(indio_dev); > + if (ret) > + return ret; > + > + if (readval) > ret = regmap_read(st->regmap, reg, readval); > - if (ret) > - goto err_unlock; > - } else { > + else > ret = regmap_write(st->regmap, reg, writeval); > - } > -err_unlock: > - mutex_unlock(&st->lock); > + > + iio_device_release_direct_mode(indio_dev); > > return ret; > } > @@ -495,18 +495,15 @@ 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; > } I think the lock can be fully removed from struct ad7768_state if it isn't being used anymore (and remove mutex_init() in probe()).