Message-ID: <9d0ddee1-6f50-0fe9-2efa-a31f1e239aa6@kernel.org>
Date:   Sat, 12 Nov 2016 17:15:34 +0000
From:   Jonathan Cameron <jic23@...nel.org>
To:     Peter Rosin <peda@...ntia.se>, linux-kernel@...r.kernel.org
Cc:     Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Daniel Baluta <daniel.baluta@...el.com>,
        Slawomir Stepien <sst@...zta.fm>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-iio@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v4 0/8] IIO wrapper drivers, dpot-dac and
 envelope-detector

On 08/11/16 11:58, Peter Rosin wrote:
> Hi!
> 
> This is a respin with a handful of nitpicks fixed from v3. No major
> changes. And a couple of acks was added too, thanks! I also added
> Thomas Gleixner as Cc, since Jonathan was hoping for some comments
> on the somewhat odd interrupt handling in patch 8/8 (but perhaps
> plumbers-week isn't the best week to hope for that).
> 
> 
> These two drivers share the fact that they wrap another iio channel,
> and I use the first in combination with the second, which is why I'm
> submitting them as a pair.
> 
> The first driver is a simple wrapper converting an iio dpot into an
> iio dac. It only changes the unit and scale. It also does not add any
> fancy iio buffer support that I don't need. I suppose that can be
> added. By someone else :-)
I'll probably get to it sooner or later if no one else jumps on it.
> 
> The second driver (the envelope detector) is more involved. It also
> explains why I need the dpot-dac driver. I wanted the envelope
> detector to be generic and work with any dac, but I had a dpot...
> 
> But before those two new drivers, there is some infrastructure added
> to provide available values for a channel.
> 
> One thing I still don't like is that the irq needs to be changed for cases
> where it is only ever interesting with the 'invert' variant, and it may not
> work to set up the irq the wrong way first. For the TSE-850, this does not
> matter, since we have a mux on the envelope detector input and can make use
> of both 'invert' and 'normal' for different signals (we could have gotten
> by with only 'invert' since the only signals we are measuring that are
> 'normal' are also DC signals and can thus be detected both from below and
> from above), but it is nice to have it both ways. The only way out of this
> is a devicetree thing. I suppose it will have to be added by whomever needs
> it whenever that is...
> 
> I also wonder if the "new" *_available ABI should perhaps be documented
> for all variants directly in sysfs-bus-iio instead of doing it in a driver
> specific maner that I did? But that can be fixed later by someone more
> capable than me :-)
You doubt yourself too much ;)  Some one with fewer inhibitions you mean!

Anyhow, just thought I'd add that I like this series very much.
It's a nice interesting use of the infrastructures.  Good to see people
are getting more adventurous all the time.

Also always nice when someone else picks up a patch I dropped years ago
and does the remaining hard work to get it in ;)

There is a limited window left obviously if we want to adjust that ABI
so shout soon or it'll be there for ever *muhahahaha*

Jonathan
> 
> v3 -> v4
> - gained acks from Rob for the three bindings patches
> - gained ack from Daniel for the core _available patch (1/8)
> - dropped the type argument from iio_read_avail_channel_raw(), since
>   raw values are assumed to be of type IIO_VAL_INT anyway
> - add some more words about what iio_read_avail_channel_raw() does
> - rebased onto v4.9-rc4
> 
> dpot-dac:
> - adjust to changed signature of iio_read_avail_channel_raw()
> - one instance of s/the channels supports/the channel supports/
> - drop surplus s64 cast in dpot_dac_channel_max_ohms()
> 
> envelope-detector
> - the envelope-detector module is called envelope-detector
> 
> 
> v2 -> v3
> - add some missing @foo comments in iio.h in the initial forward ported patch
> - killed some buffer overflow problems in the initial forward ported patch
> - add inkern.c helpers for the new available attributes to avoid viral
>   boilerplating in the future (also add support for finding max of
>   IIO_AVAIL_LISTs of IIO_VAL_INTs)
> - add ABI docs for new ABI of mcp4531 (out_resistance_raw_available)
>   and an example in the commit message
> 
> dpot-dac:
> - two more counts of s/assumed the that the/assumed that the/   *blush*
> - add ABI docs for new ABI (out_voltageY_raw_available)
> 
> envelope detector:
> - move device attributes 'compare_interval_ms' and 'invert' to extended
>   channel attributes (out_altvoltage0_compare_interval and
>   out_altvoltage0_invert) as they really are about the channel and not
>   the device
> - kill "dpot-dac,max-ohms = <100000>;" in the devicetree example
> 
> 
> v1 -> v2
> - provide out_resistanceX_raw_available channel attribute in mcp4531 dpot
> 
> dpot-dac:
> - change Vref to vref
> - the module will be called dpot-dac (in Kconfig help)
> - removed a 'the'
> - removed (s64) cast
> - make the channel indexed, makes libiio find the channel (tested with 0.5)
> - add a comment on how integer scale is converted to fractional scale
>   and clarify the code a bit
> - dig out max-ohms by looking at scale and maximum available raw value
>   from the dpot channel and drop the 'dpot-dac,max-ohms' devicetree property
> - provide out_voltageX_raw_available channel attribute
> 
> envelope-detector:
> - change compatible from envelope-detector to axentia,tse850-envelope-detector
> - remove envelope-detector,invert and envelope-detector,comp-interval-ms from
>   devicetree and add them as iio device attributes instead
> - make the channel indexed, makes libiio find the channel (tested with 0.5)
> - reorder struct envelope to better indicate what is covered by read_lock
> - add comment on interaction between envelope_detector_comp_latch (renamed
>   from envelope_detector_latch) and envelope_detector_comp_isr (renamed
>   from envelope_detector_isr)
> - fixup a problem in envelope_detector_comp_latch where interrupts pending
>   from when the interrupt has been disabled interferes with expected
>   operation
> - slight rewrite of the initial high/low assignments
> - use a better name when requesting the interrupt
> - dig out dac_max by looking at scale and maximum available raw value
>   from the dac channel and drop the 'envelope-detector,dac-max' devicetree
>   property
> 
> Cheers,
> Peter
> 
> Jonathan Cameron (1):
>   iio:core: add a callback to allow drivers to provide _available
>     attributes
> 
> Peter Rosin (7):
>   iio: inkern: add helpers to query available values from channels
>   iio: mcp4531: provide range of available raw values
>   dt-bindings: add axentia to vendor-prefixes
>   dt-bindings: iio: document dpot-dac bindings
>   iio: dpot-dac: DAC driver based on a digital potentiometer
>   dt-bindings: iio: document envelope-detector bindings
>   iio: envelope-detector: ADC driver based on a DAC and a comparator
> 
>  .../testing/sysfs-bus-iio-adc-envelope-detector    |  36 ++
>  .../ABI/testing/sysfs-bus-iio-dac-dpot-dac         |   8 +
>  .../testing/sysfs-bus-iio-potentiometer-mcp4531    |   8 +
>  .../bindings/iio/adc/envelope-detector.txt         |  54 +++
>  .../devicetree/bindings/iio/dac/dpot-dac.txt       |  41 ++
>  .../devicetree/bindings/vendor-prefixes.txt        |   1 +
>  MAINTAINERS                                        |  17 +
>  drivers/iio/adc/Kconfig                            |  10 +
>  drivers/iio/adc/Makefile                           |   1 +
>  drivers/iio/adc/envelope-detector.c                | 422 +++++++++++++++++++++
>  drivers/iio/dac/Kconfig                            |  10 +
>  drivers/iio/dac/Makefile                           |   1 +
>  drivers/iio/dac/dpot-dac.c                         | 266 +++++++++++++
>  drivers/iio/industrialio-core.c                    | 259 +++++++++++--
>  drivers/iio/inkern.c                               | 104 +++++
>  drivers/iio/potentiometer/mcp4531.c                | 104 +++--
>  include/linux/iio/consumer.h                       |  28 ++
>  include/linux/iio/iio.h                            |  46 +++
>  include/linux/iio/types.h                          |   5 +
>  19 files changed, 1346 insertions(+), 75 deletions(-)
>  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-adc-envelope-detector
>  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-dac-dpot-dac
>  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-potentiometer-mcp4531
>  create mode 100644 Documentation/devicetree/bindings/iio/adc/envelope-detector.txt
>  create mode 100644 Documentation/devicetree/bindings/iio/dac/dpot-dac.txt
>  create mode 100644 drivers/iio/adc/envelope-detector.c
>  create mode 100644 drivers/iio/dac/dpot-dac.c
> 

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