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Message-ID: <20220227130546.5ed0bae1@jic23-huawei>
Date: Sun, 27 Feb 2022 13:05:46 +0000
From: Jonathan Cameron <jic23@...nel.org>
To: Liam Beguin <liambeguin@...il.com>
Cc: peda@...ntia.se, andy.shevchenko@...il.com, lars@...afoo.de,
linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
devicetree@...r.kernel.org, robh+dt@...nel.org
Subject: Re: [PATCH v15 00/10] iio: afe: add temperature rescaling support
On Sun, 27 Feb 2022 12:55:59 +0000
Jonathan Cameron <jic23@...nel.org> wrote:
> On Sat, 12 Feb 2022 21:57:29 -0500
> Liam Beguin <liambeguin@...il.com> wrote:
>
> > Jonathan, Peter, Andy,
> >
> > This series focuses on adding temperature rescaling support to the IIO
> > Analog Front End (AFE) driver.
> >
> > The main changes to the AFE driver include an initial Kunit test suite,
> > support for IIO_VAL_INT_PLUS_{NANO,MICRO} scales, and support for RTDs
> > and temperature transducer sensors.
> >
> > Thanks for your time,
> > Liam
>
> Hi Liam,
>
> I was waiting for Andy to reply to this. Took a quick look back at
> what was outstanding and realised he had given a
> Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>
> for v13.
Actually given the units.h change is a perhaps non trivial perhaps that's
why you dropped Andy's RB. I'll still apply the series, but it Andy
confirms his view on that tag before I push this out as something I can't
rebase I'll add it if appropriate.
Thanks,
Jonathan
>
> I'm assuming there wasn't a strong reason to drop that in the meantime
> and it's a simple omission / crossed emails issue.
>
> As such,
>
> Series applied to the togreg branch of iio.git and pushed out
> as testing to get some build coverage from 0-day.
>
> Thanks,
>
> Jonathan
>
> >
> > Changes since v14:
> > - Revert units.h changes in favor of "raw" values
> >
> > Changes since v13:
> > - fix SI prefix in rescale_temp_sense_rtd_props()
> > - add comment explaining SI prefixes are sometimes used as mathematical
> > multipliers with no particular physical meaning associated.
> >
> > Changes since v12:
> > - rebase on latest testing branch
> > - fix copyright holder in newly created header file
> > - add myself as a copyright holder of the iio-rescale.c driver at
> > Peter's suggestion
> > - fix undefined behavior on left-shift operation
> >
> > Changes since v11:
> > - update commits with my personal email since all this work was done on
> > my own time
> > - apply Peter's Reviewed-by to my local tree
> > - fix use of units.h
> > - make use of units.h more consistently in iio-rescale.c and in the
> > tests
> > - fix #include ordering
> > - treat 04/16 as a fix. Move it, and add a Fixes: tag
> > - fix undefined behavior on left-shift operation
> > - add comment about fract_mult with iio_str_to_fixpoint()
> > - reword commit message for 14/16, based on Andy's comments
> >
> > Changes since v10:
> > - apply Andy's suggestion for offset calculations
> > - make use of units.h more consistently
> >
> > Changes since v9:
> > - make use of linux/units.h
> > - reorder commits, fix fract_log2 before merging fract
> > - keep fractional representation when not overflowing
> >
> > Changes since v8:
> > - reword comment
> > - fix erroneous 64-bit division
> > - optimize and use 32-bit divisions when values are know to not overflow
> > - keep IIO_VAL_FRACTIONAL scale when possible, if not default to fixed
> > point
> > - add test cases
> > - use nano precision in test cases
> > - simplify offset calculation in rtd_props()
> >
> > Changes since v7:
> > - drop gcd() logic in rescale_process_scale()
> > - use div_s64() instead of do_div() for signed 64-bit divisions
> > - combine IIO_VAL_FRACTIONAL and IIO_VAL_FRACTIONAL_LOG2 scale cases
> > - switch to INT_PLUS_NANO when accuracy is lost with FRACTIONAL scales
> > - rework test logic to allow for small relative error
> > - rename test variables to align error output messages
> >
> > Changes since v6:
> > - rework IIO_VAL_INT_PLUS_{NANO,MICRO} based on Peter's suggestion
> > - combine IIO_VAL_INT_PLUS_{NANO,MICRO} cases
> > - add test cases for negative IIO_VAL_INT_PLUS_{NANO,MICRO} corner cases
> > - force use of positive integers with gcd()
> > - reduce risk of integer overflow in IIO_VAL_FRACTIONAL_LOG2
> > - fix duplicate symbol build error
> > - apply Reviewed-by
> >
> > Changes since v5:
> > - add include/linux/iio/afe/rescale.h
> > - expose functions use to process scale and offset
> > - add basic iio-rescale kunit test cases
> > - fix integer overflow case
> > - improve precision for IIO_VAL_FRACTIONAL_LOG2
> >
> > Changes since v4:
> > - only use gcd() when necessary in overflow mitigation
> > - fix INT_PLUS_{MICRO,NANO} support
> > - apply Reviewed-by
> > - fix temperature-transducer bindings
> >
> > Changes since v3:
> > - drop unnecessary fallthrough statements
> > - drop redundant local variables in some calculations
> > - fix s64 divisions on 32bit platforms by using do_div
> > - add comment describing iio-rescaler offset calculation
> > - drop unnecessary MAINTAINERS entry
> >
> > Changes since v2:
> > - don't break implicit offset truncations
> > - make a best effort to get a valid value for fractional types
> > - drop return value change in iio_convert_raw_to_processed_unlocked()
> > - don't rely on processed value for offset calculation
> > - add INT_PLUS_{MICRO,NANO} support in iio-rescale
> > - revert generic implementation in favor of temperature-sense-rtd and
> > temperature-transducer
> > - add separate section to MAINTAINERS file
> >
> > Changes since v1:
> > - rebase on latest iio `testing` branch
> > - also apply consumer scale on integer channel scale types
> > - don't break implicit truncation in processed channel offset
> > calculation
> > - drop temperature AFE flavors in favor of a simpler generic
> > implementation
> >
> > Liam Beguin (10):
> > iio: afe: rescale: expose scale processing function
> > iio: afe: rescale: add INT_PLUS_{MICRO,NANO} support
> > iio: afe: rescale: add offset support
> > iio: afe: rescale: fix accuracy for small fractional scales
> > iio: afe: rescale: reduce risk of integer overflow
> > iio: test: add basic tests for the iio-rescale driver
> > iio: afe: rescale: add RTD temperature sensor support
> > iio: afe: rescale: add temperature transducers
> > dt-bindings: iio: afe: add bindings for temperature-sense-rtd
> > dt-bindings: iio: afe: add bindings for temperature transducers
> >
> > .../iio/afe/temperature-sense-rtd.yaml | 101 +++
> > .../iio/afe/temperature-transducer.yaml | 114 +++
> > drivers/iio/afe/iio-rescale.c | 283 ++++++-
> > drivers/iio/test/Kconfig | 10 +
> > drivers/iio/test/Makefile | 1 +
> > drivers/iio/test/iio-test-rescale.c | 710 ++++++++++++++++++
> > include/linux/iio/afe/rescale.h | 36 +
> > 7 files changed, 1220 insertions(+), 35 deletions(-)
> > create mode 100644 Documentation/devicetree/bindings/iio/afe/temperature-sense-rtd.yaml
> > create mode 100644 Documentation/devicetree/bindings/iio/afe/temperature-transducer.yaml
> > create mode 100644 drivers/iio/test/iio-test-rescale.c
> > create mode 100644 include/linux/iio/afe/rescale.h
> >
> > Range-diff against v14:
> > -: ------------ > 1: ee26b0eeac65 iio: afe: rescale: expose scale processing function
> > 1: a510097c83f1 ! 2: 78f9d37575a5 iio: afe: rescale: add INT_PLUS_{MICRO,NANO} support
> > @@ Commit message
> > Reviewed-by: Peter Rosin <peda@...ntia.se>
> >
> > ## drivers/iio/afe/iio-rescale.c ##
> > -@@
> > - #include <linux/of_device.h>
> > - #include <linux/platform_device.h>
> > - #include <linux/property.h>
> > -+#include <linux/units.h>
> > -
> > - #include <linux/iio/afe/rescale.h>
> > - #include <linux/iio/consumer.h>
> > @@ drivers/iio/afe/iio-rescale.c: int rescale_process_scale(struct rescale *rescale, int scale_type,
> > int *val, int *val2)
> > {
> > @@ drivers/iio/afe/iio-rescale.c: int rescale_process_scale(struct rescale *rescale
> > + return scale_type;
> > + case IIO_VAL_INT_PLUS_NANO:
> > + case IIO_VAL_INT_PLUS_MICRO:
> > -+ mult = scale_type == IIO_VAL_INT_PLUS_NANO ? GIGA : MEGA;
> > ++ mult = scale_type == IIO_VAL_INT_PLUS_NANO ? 1000000000L : 1000000L;
> > +
> > + /*
> > + * For IIO_VAL_INT_PLUS_{MICRO,NANO} scale types if either *val
> > 2: 8f2f2699a9b4 ! 3: 5be82bd72453 iio: afe: rescale: add offset support
> > @@ drivers/iio/afe/iio-rescale.c: int rescale_process_scale(struct rescale *rescale
> > + *val = div_s64(tmp, scale) + schan_off;
> > + return IIO_VAL_INT;
> > + case IIO_VAL_INT_PLUS_NANO:
> > -+ tmp = (s64)rescale->offset * GIGA;
> > -+ tmp2 = ((s64)scale * GIGA) + scale2;
> > ++ tmp = (s64)rescale->offset * 1000000000LL;
> > ++ tmp2 = ((s64)scale * 1000000000LL) + scale2;
> > + *val = div64_s64(tmp, tmp2) + schan_off;
> > + return IIO_VAL_INT;
> > + case IIO_VAL_INT_PLUS_MICRO:
> > -+ tmp = (s64)rescale->offset * MEGA;
> > -+ tmp2 = ((s64)scale * MEGA) + scale2;
> > ++ tmp = (s64)rescale->offset * 1000000LL;
> > ++ tmp2 = ((s64)scale * 1000000LL) + scale2;
> > + *val = div64_s64(tmp, tmp2) + schan_off;
> > + return IIO_VAL_INT;
> > + default:
> > 3: 2efa970bad26 ! 4: 95ec184759f6 iio: afe: rescale: fix accuracy for small fractional scales
> > @@ drivers/iio/afe/iio-rescale.c: int rescale_process_scale(struct rescale *rescale
> > + return IIO_VAL_INT_PLUS_NANO;
> > case IIO_VAL_INT_PLUS_NANO:
> > case IIO_VAL_INT_PLUS_MICRO:
> > - mult = scale_type == IIO_VAL_INT_PLUS_NANO ? GIGA : MEGA;
> > + mult = scale_type == IIO_VAL_INT_PLUS_NANO ? 1000000000L : 1000000L;
> > 4: 201037c0ead8 = 5: 2e1d41ef69d9 iio: afe: rescale: reduce risk of integer overflow
> > 5: a0037cc3ee90 < -: ------------ iio: afe: rescale: make use of units.h
> > 6: f8d47728f482 ! 6: 0b6c029dea1d iio: test: add basic tests for the iio-rescale driver
> > @@ drivers/iio/test/iio-test-rescale.c (new)
> > +
> > +#include <linux/gcd.h>
> > +#include <linux/overflow.h>
> > -+#include <linux/units.h>
> > +
> > +#include <linux/iio/afe/rescale.h>
> > +#include <linux/iio/iio.h>
> > @@ drivers/iio/test/iio-test-rescale.c (new)
> > + if (tmp < 0)
> > + tmp2 *= -1;
> > +
> > -+ *nano = (s64)tmp * GIGA + tmp2;
> > ++ *nano = (s64)tmp * 1000000000UL + tmp2;
> > +
> > + return ret;
> > +}
> > @@ drivers/iio/test/iio-test-rescale.c (new)
> > + return -EINVAL;
> > + }
> > +
> > -+ err = MEGA * abs(exp - real);
> > ++ err = 1000000UL * abs(exp - real);
> > +
> > + return (int)div64_u64(err, abs(exp));
> > +}
> > 7: a04685586340 ! 7: 951ea44d0f5c iio: afe: rescale: add RTD temperature sensor support
> > @@ drivers/iio/afe/iio-rescale.c: static int rescale_voltage_divider_props(struct d
> > + return ret;
> > + }
> > +
> > -+ tmp = r0 * iexc * alpha / MEGA;
> > -+ factor = gcd(tmp, MEGA);
> > -+ rescale->numerator = MEGA / factor;
> > ++ tmp = r0 * iexc * alpha / 1000000;
> > ++ factor = gcd(tmp, 1000000);
> > ++ rescale->numerator = 1000000 / factor;
> > + rescale->denominator = tmp / factor;
> > +
> > -+ rescale->offset = -1 * ((r0 * iexc) / KILO);
> > ++ rescale->offset = -1 * ((r0 * iexc) / 1000);
> > +
> > + return 0;
> > +}
> > 8: e3b716aaee50 ! 8: 56516fdc67bf iio: afe: rescale: add temperature transducers
> > @@ drivers/iio/afe/iio-rescale.c: static int rescale_temp_sense_rtd_props(struct de
> > + return ret;
> > + }
> > +
> > -+ rescale->numerator = MEGA;
> > ++ rescale->numerator = 1000000;
> > + rescale->denominator = alpha * sense;
> > +
> > + rescale->offset = div_s64((s64)offset * rescale->denominator,
> > 9: 22ae1458eb8b = 9: 8c409050990b dt-bindings: iio: afe: add bindings for temperature-sense-rtd
> > 10: 33825ad452d6 = 10: bb39296590f3 dt-bindings: iio: afe: add bindings for temperature transducers
> >
> > base-commit: cd717ac6f69db4953ca701c6220c7cb58e17f35a
>
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