From: Jonathan Cameron <jic23@kernel.org>
To: Guenter Roeck <linux@roeck-us.net>
Cc: Andreas Klinger <ak@it-klinger.de>,
devicetree@vger.kernel.org, linux-iio@vger.kernel.org,
Rob Herring <robh+dt@kernel.org>,
Jonathan Cameron <Jonathan.Cameron@huawei.com>,
Jiri Kosina <trivial@kernel.org>,
Chris Packham <chris.packham@alliedtelesis.co.nz>,
Slawomir Stepien <sst@poczta.fm>,
Krzysztof Kozlowski <krzk@kernel.org>,
Alexandre Belloni <alexandre.belloni@bootlin.com>,
Vadim Pasternak <vadimp@nvidia.com>,
Alexandru Ardelean <alexandru.ardelean@analog.com>,
linux-kernel@vger.kernel.org,
Lars-Peter Clausen <lars@metafoo.de>,
Tomasz Duszynski <tomasz.duszynski@octakon.com>
Subject: Re: [PATCH 2/2] iio: chemical: Add driver support for sgp40
Date: Sun, 1 Aug 2021 18:01:11 +0100 [thread overview]
Message-ID: <20210801180111.28a1c4d1@jic23-huawei> (raw)
In-Reply-To: <42e31edc-445c-06ac-dd3a-80db1b439996@roeck-us.net>
On Sat, 31 Jul 2021 11:06:25 -0700
Guenter Roeck <linux@roeck-us.net> wrote:
> On 7/31/21 9:39 AM, Jonathan Cameron wrote:
> > On Tue, 27 Jul 2021 18:35:19 +0200
> > Andreas Klinger <ak@it-klinger.de> wrote:
> >
> >> sgp40 is a gas sensor used for measuring the air quality.
> >>
> >> This driver is reading the raw resistance value which can be passed to
> >> a userspace algorithm for further calculation.
> >>
> >> The raw value is also used to calculate an estimated absolute voc index
> >> in the range from 0 to 500. For this purpose the raw_mean value of the
> >> resistance for which the index value is 250 might be set up as a
> >> calibration step.
> >>
> >> Compensation of relative humidity and temperature is supported and can
> >> be used by writing to device attributes of the driver.
> >>
> >> There is a predecesor sensor type (sgp30) already existing. This driver
> >> module was not extended because the new sensor is quite different in its
> >> i2c telegrams.
> >>
> >> Signed-off-by: Andreas Klinger <ak@it-klinger.de>
> >
> > Hi Andreas,
> >
> > Non standard ABI in here, so we are missing documentation in Documentation/ABI/testing/sysfs-bus-iio-*
> >
> > Otherwise a few suggestions inline.
> >
> > Thanks,
> >
> > Jonathan
> >
> >
> >> ---
> [ ... ]
>
> >> +static int sgp40_read_raw(struct iio_dev *indio_dev,
> >> + struct iio_chan_spec const *chan, int *val,
> >> + int *val2, long mask)
> >> +{
> >> + struct sgp40_data *data = iio_priv(indio_dev);
> >> + int ret;
> >> + u16 raw;
> >> + int voc;
> >> +
> >> + switch (mask) {
> >> + case IIO_CHAN_INFO_RAW:
> >> + mutex_lock(&data->lock);
> >> + ret = sgp40_measure_raw(data, &raw);
> >> + if (ret) {
> >> + mutex_unlock(&data->lock);
> >> + return ret;
> >> + }
> >> + *val = raw;
> >> + ret = IIO_VAL_INT;
> >> + mutex_unlock(&data->lock);
> >> + break;
> >> + case IIO_CHAN_INFO_PROCESSED:
> >> + mutex_lock(&data->lock);
> >> + ret = sgp40_measure_raw(data, &raw);
> >> + if (ret) {
> >> + mutex_unlock(&data->lock);
> >> + return ret;
> >> + }
> >> + ret = sgp40_calc_voc(data, raw, &voc);
> >> + if (ret) {
> >> + mutex_unlock(&data->lock);
> >> + return ret;
> >> + }
> >> + *val = voc;
> >> + ret = IIO_VAL_INT;
> >> + mutex_unlock(&data->lock);
> >
> > You are holding the lock longer than needed - it would be good
> > to reduce this, hopefully removing the need for unlocking separately
> > in each of the error paths.
> >
> >> + break;
> >> + default:
> >> + return -EINVAL;
> >> + }
> >> +
> >> + return ret;
> >
> > Drop this as you can't get here.
> >
>
> Are you sure ? I see several "break;" above.
Doh! In that case, return directly where it has break above so we don't
need to go see if anything else happens in those paths.
>
> Guenter
prev parent reply other threads:[~2021-08-01 16:58 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-27 16:35 [PATCH 2/2] iio: chemical: Add driver support for sgp40 Andreas Klinger
2021-07-31 16:39 ` Jonathan Cameron
2021-07-31 18:06 ` Guenter Roeck
2021-08-01 17:01 ` Jonathan Cameron [this message]
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