From: Jonathan Cameron <jonathan.cameron@huawei.com>
To: Andrea Merello <andrea.merello@gmail.com>
Cc: Jonathan Cameron <jic23@kernel.org>,
<patrick.havelange@essensium.com>,
<paresh.chaudhary@rockwellcollins.com>, <pmeerw@pmeerw.net>,
<lars@metafoo.de>, <knaack.h@gmx.de>,
Matthew Weber <matthew.weber@rockwellcollins.com>,
Colin King <colin.king@canonical.com>,
<linux-iio@vger.kernel.org>
Subject: Re: [PATCH 1/3] iio: max31856: add option for setting mains filter rejection frequency
Date: Thu, 17 Oct 2019 13:32:10 +0100 [thread overview]
Message-ID: <20191017133210.00002799@huawei.com> (raw)
In-Reply-To: <CAN8YU5Ogcp8ERkxntTVQH3EoJF7h61VCONPXEaP-kvpx8EmS+g@mail.gmail.com>
On Wed, 16 Oct 2019 15:14:20 +0200
Andrea Merello <andrea.merello@gmail.com> wrote:
> Il giorno dom 6 ott 2019 alle ore 09:54 Jonathan Cameron
> <jic23@kernel.org> ha scritto:
> >
> > On Mon, 23 Sep 2019 14:17:12 +0200
> > Andrea Merello <andrea.merello@gmail.com> wrote:
> >
> > > This sensor has an embedded notch filter for reducing interferences caused
> > > by the power mains. This filter can be tuned to reject either 50Hz or 60Hz
> > > (and harmonics).
> > >
> > > Currently the said setting is left alone (the sensor defaults to 60Hz).
> > > This patch introduces a IIO attribute that allows the user to set the said
> > > filter to the desired frequency.
> > >
> > > NOTE: this has been intentionally not tied to any DT property to allow
> > > the configuration of this setting from userspace, e.g. with a GUI or by
> > > reading a configuration file, or maybe reading a GPIO tied to a physical
> > > switch or accessing some device that can autodetect the line frequency.
> > >
> > > Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
> > This one is not something that can be expect to be known from the setup
> > of the device as it will depend on local mains frequency.
> >
> > So fine, to have it as a userspace control, but the name is too generic.
> > We already have a number of filter attributes and we should try to
> > work out how to bring it inline with them.
>
> Sure
>
> > in_X_filter_low_pass_3db_frequency
> > in_X_filter_high_pass_3db_frequency
> >
> > So would,
> > in_X_filter_notch_center_frequency work?
> > ( I suppose we should use the American spelling ;)
>
> Yes, it seems OK in this case. I will produce a V2 with this modification.
>
> > This kind of ignores the harmonics aspect but at least documents the
> > main frequency being blocked.
>
> I think this is perfectly fine: the user wants to set the notch filter
> center frequency to either 60Hz or 50Hz to match the line frequency,
> then she/he expects the filter to simply "work" somehow; IMO the
> harmonic thing does not needed to be explicit.
>
> > There is a slight complexity that we have devices that have dual
> > notchfilters (50 and 60Hz) and ones where you can turn it off entirely.
> >
> > I suppose no value would count as off and we could perhaps use a list
> > for both on at the same time (though that's a bit horrible).
>
> IMHO it seems reasonable. Maybe for all-off and both-on conditions we
> could also use magic strings like i.e. "all" and "off".
I go with 'maybe' on that one. Need to think about whether that is just
a partial solution as we will probably find a device with 3 options that only
supports any 2 at one time. That would still need a more complex interface.
Will think on this.
Jonathan
>
> > > ---
> > > drivers/iio/temperature/max31856.c | 49 ++++++++++++++++++++++++++++++
> > > 1 file changed, 49 insertions(+)
> > >
> > > diff --git a/drivers/iio/temperature/max31856.c b/drivers/iio/temperature/max31856.c
> > > index 73ed550e3fc9..d12613f7ba3c 100644
> > > --- a/drivers/iio/temperature/max31856.c
> > > +++ b/drivers/iio/temperature/max31856.c
> > > @@ -23,6 +23,7 @@
> > > #define MAX31856_CR0_1SHOT BIT(6)
> > > #define MAX31856_CR0_OCFAULT BIT(4)
> > > #define MAX31856_CR0_OCFAULT_MASK GENMASK(5, 4)
> > > +#define MAX31856_CR0_FILTER_50HZ BIT(0)
> > > #define MAX31856_TC_TYPE_MASK GENMASK(3, 0)
> > > #define MAX31856_FAULT_OVUV BIT(1)
> > > #define MAX31856_FAULT_OPEN BIT(0)
> > > @@ -63,6 +64,7 @@ static const struct iio_chan_spec max31856_channels[] = {
> > > struct max31856_data {
> > > struct spi_device *spi;
> > > u32 thermocouple_type;
> > > + bool filter_50hz;
> > > };
> > >
> > > static int max31856_read(struct max31856_data *data, u8 reg,
> > > @@ -123,6 +125,11 @@ static int max31856_init(struct max31856_data *data)
> > > reg_cr0_val &= ~MAX31856_CR0_1SHOT;
> > > reg_cr0_val |= MAX31856_CR0_AUTOCONVERT;
> > >
> > > + if (data->filter_50hz)
> > > + reg_cr0_val |= MAX31856_CR0_FILTER_50HZ;
> > > + else
> > > + reg_cr0_val &= ~MAX31856_CR0_FILTER_50HZ;
> > > +
> > > return max31856_write(data, MAX31856_CR0_REG, reg_cr0_val);
> > > }
> > >
> > > @@ -249,12 +256,53 @@ static ssize_t show_fault_oc(struct device *dev,
> > > return show_fault(dev, MAX31856_FAULT_OPEN, buf);
> > > }
> > >
> > > +static ssize_t show_filter(struct device *dev,
> > > + struct device_attribute *attr,
> > > + char *buf)
> > > +{
> > > + struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> > > + struct max31856_data *data = iio_priv(indio_dev);
> > > +
> > > + return sprintf(buf, "%d\n", data->filter_50hz ? 50 : 60);
> > > +}
> > > +
> > > +static ssize_t set_filter(struct device *dev,
> > > + struct device_attribute *attr,
> > > + const char *buf,
> > > + size_t len)
> > > +{
> > > + struct iio_dev *indio_dev = dev_to_iio_dev(dev);
> > > + struct max31856_data *data = iio_priv(indio_dev);
> > > + unsigned int freq;
> > > + int ret;
> > > +
> > > + ret = kstrtouint(buf, 10, &freq);
> > > + if (ret)
> > > + return ret;
> > > +
> > > + switch (freq) {
> > > + case 50:
> > > + data->filter_50hz = true;
> > > + break;
> > > + case 60:
> > > + data->filter_50hz = false;
> > > + break;
> > > + default:
> > > + return -EINVAL;
> > > + }
> > > +
> > > + max31856_init(data);
> > > + return len;
> > > +}
> > > +
> > > static IIO_DEVICE_ATTR(fault_ovuv, 0444, show_fault_ovuv, NULL, 0);
> > > static IIO_DEVICE_ATTR(fault_oc, 0444, show_fault_oc, NULL, 0);
> > > +static IIO_DEVICE_ATTR(filter, 0644, show_filter, set_filter, 0);
> > >
> > > static struct attribute *max31856_attributes[] = {
> > > &iio_dev_attr_fault_ovuv.dev_attr.attr,
> > > &iio_dev_attr_fault_oc.dev_attr.attr,
> > > + &iio_dev_attr_filter.dev_attr.attr,
> > > NULL,
> > > };
> > >
> > > @@ -280,6 +328,7 @@ static int max31856_probe(struct spi_device *spi)
> > >
> > > data = iio_priv(indio_dev);
> > > data->spi = spi;
> > > + data->filter_50hz = false;
> > >
> > > spi_set_drvdata(spi, indio_dev);
> > >
> >
next prev parent reply other threads:[~2019-10-17 12:32 UTC|newest]
Thread overview: 60+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-23 12:17 [PATCH 0/3] iio: max31856: provide more configuration options Andrea Merello
2019-09-23 12:17 ` [PATCH 1/3] iio: max31856: add option for setting mains filter rejection frequency Andrea Merello
2019-10-06 7:54 ` Jonathan Cameron
2019-10-16 13:14 ` Andrea Merello
2019-10-17 12:32 ` Jonathan Cameron [this message]
2019-10-18 13:46 ` Andrea Merello
2019-10-22 9:34 ` Jonathan Cameron
2019-10-23 8:29 ` Andrea Merello
2019-10-27 9:22 ` Jonathan Cameron
2019-10-28 7:32 ` Andrea Merello
2019-11-02 14:17 ` Jonathan Cameron
2019-11-04 13:51 ` Andrea Merello
2019-09-23 12:17 ` [PATCH 2/3] iio: max31856: add support for configuring the HW averaging Andrea Merello
2019-10-06 7:55 ` Jonathan Cameron
2019-10-16 13:33 ` Andrea Merello
2019-10-17 12:34 ` Jonathan Cameron
2019-10-18 13:47 ` Andrea Merello
2019-09-23 12:17 ` [PATCH 3/3] iio: max31856: add support for runtime-configuring the thermocouple type Andrea Merello
2019-10-06 7:58 ` Jonathan Cameron
2019-10-16 13:43 ` Andrea Merello
2019-10-17 12:35 ` Jonathan Cameron
2019-10-18 13:48 ` Andrea Merello
2019-11-11 15:35 ` [v2 0/9] iio: max31856: provide more configuration options Andrea Merello
2019-11-11 15:35 ` [v2 1/9] iio: max31856: add option for setting mains filter rejection frequency Andrea Merello
2019-11-11 22:59 ` Matt Ranostay
2019-11-16 14:29 ` Jonathan Cameron
2019-11-11 15:35 ` [v2 2/9] Documentation: ABI: document IIO in_temp_filter_notch_center_frequency file Andrea Merello
2019-11-11 15:35 ` [v2 3/9] iio: max31856: add support for configuring the HW averaging Andrea Merello
2019-11-11 23:01 ` Matt Ranostay
2019-11-11 15:35 ` [v2 4/9] RFC: iio: core: add char type for sysfs attributes Andrea Merello
2019-11-16 14:45 ` Jonathan Cameron
2019-11-11 15:35 ` [v2 5/9] iio: core: add thermocouple_type standard attribute Andrea Merello
2019-11-11 15:35 ` [v2 6/9] Documentation: ABI: document IIO thermocouple_type file Andrea Merello
2019-11-16 14:47 ` Jonathan Cameron
2019-11-11 15:35 ` [v2 7/9] iio: max31856: add support for runtime-configuring the thermocouple type Andrea Merello
2019-11-16 14:49 ` Jonathan Cameron
2019-11-11 15:35 ` [v2 8/9] RFC/RFT: iio: maxim_thermocouple: add thermocouple_type sysfs attribute Andrea Merello
2019-11-16 14:51 ` Jonathan Cameron
2019-11-11 15:35 ` [v2 9/9] dt-bindings: iio: maxim_thermocouple: document new 'compatible' strings Andrea Merello
2019-11-14 22:12 ` Rob Herring
2019-11-20 14:47 ` [v3 0/9] iio: max31856: provide more configuration options Andrea Merello
2019-11-20 14:47 ` [v3 1/9] iio: max31856: add option for setting mains filter rejection frequency Andrea Merello
2019-11-23 12:30 ` Jonathan Cameron
2019-11-20 14:47 ` [v3 2/9] Documentation: ABI: document IIO in_temp_filter_notch_center_frequency file Andrea Merello
2019-11-23 12:31 ` Jonathan Cameron
2019-11-20 14:47 ` [v3 3/9] iio: max31856: add support for configuring the HW averaging Andrea Merello
2019-11-23 12:32 ` Jonathan Cameron
2019-11-20 14:47 ` [v3 4/9] RFC: iio: core: add char type for sysfs attributes Andrea Merello
2019-11-23 12:33 ` Jonathan Cameron
2019-11-20 14:47 ` [v3 5/9] iio: core: add thermocouple_type standard attribute Andrea Merello
2019-11-23 12:36 ` Jonathan Cameron
2019-11-20 14:47 ` [v3 6/9] Documentation: ABI: document IIO thermocouple_type file Andrea Merello
2019-11-23 12:37 ` Jonathan Cameron
2019-11-20 14:47 ` [v3 7/9] iio: max31856: add support for runtime-configuring the thermocouple type Andrea Merello
2019-11-23 12:40 ` Jonathan Cameron
2019-11-23 12:41 ` Jonathan Cameron
2019-11-20 14:47 ` [v3 8/9] RFC/RFT: iio: maxim_thermocouple: add thermocouple_type sysfs attribute Andrea Merello
2019-11-23 12:46 ` Jonathan Cameron
2019-11-20 14:47 ` [v3 9/9] dt-bindings: iio: maxim_thermocouple: document new 'compatible' strings Andrea Merello
2019-11-23 12:46 ` Jonathan Cameron
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