linux-kernel - Re: [PATCH v3 0/2] Adding support for Microchip MCP3564 ADC family

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Date:   Sat, 5 Aug 2023 18:08:42 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     <marius.cristea@...rochip.com>
Cc:     <lars@...afoo.de>, <robh+dt@...nel.org>,
        <krzysztof.kozlowski+dt@...aro.org>, <conor+dt@...nel.org>,
        <linux-iio@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 0/2] Adding support for Microchip MCP3564 ADC family

On Fri, 4 Aug 2023 17:28:18 +0300
<marius.cristea@...rochip.com> wrote:

> From: Marius Cristea <marius.cristea@...rochip.com>
> 
> Adding support for Microchip family of 153.6 ksps, Low-Noise 16/24-Bit
> Delta-Sigma ADCs with an SPI interface. This driver covers the following part
> numbers:
>  - MCP3561, MCP3562, MCP3564, MCP3561R, MCP3562R, MCP3564R,
>  - MCP3461, MCP3462, MCP3464, MCP3461R, MCP3462R and MCP3464R.
> 
> Differences related to previous patch:
> v3:
> - fix review comments:
>   - fix and update the device tree bindings
>   - enable "auto_zeroing_ref_enable" attribute only
>     when internal reference is used
>   - remove unused headers
>   - fix comments (kernel-docs)
>   - remove scan_type
>   - replace "extend_name" with read_label
>   - print label for each channel (label could be added into the dt)
>   - add comment to explain the maximum channels numbers
>   - add protection around critical region
>   - fallback compatible in device tree to deal with some newer part number
>   
> - Open questions:
>   - whether or not to add a spi-mux type of thing to deal with the part number
>     address in case there are multiple devices connected to the same chip
>     select.

I'd failed to register (until noticing it in a review a few mins ago) that we have
have precedence for devices doing this device-address in the SPI transfer thing.
The mcp3911 does it as well.  Obviously that doesn't rule out us doing something
different with this one though.  

I think we should take the view this is relatively uncommon and go with this
simple vendor specific dt-binding approach.  Always nice to do something more
general, but sometimes it isn't worth the effort.


>   - discussion related to the "custom property". Last time around a consensus
>     wasn't reached. 
> 
> v2:
> - fix review comments:
>   - change the device tree bindings
>   - change the ADC channel creation (starting from DT)
>   - use defines, masks and FIELD_PREP() instead of hardcoded values
>   - mode the PGA from Hardware Gain to scale
>   - add a current output channel from burnout current
>   - fix coding style issues
>   - use self-explanatory naming to drop the comment 
> - renumbered the versioning (start with v1 instead of v0)
> 
> v1:
> - first version committed to review
> 
> Marius Cristea (2):
>   dt-bindings: iio: adc: adding MCP3564 ADC
>   iio: adc: adding support for MCP3564 ADC
> 
>  .../ABI/testing/sysfs-bus-iio-adc-mcp3564     |   53 +
>  .../bindings/iio/adc/microchip,mcp3564.yaml   |  200 +++
>  MAINTAINERS                                   |    7 +
>  drivers/iio/adc/Kconfig                       |   13 +
>  drivers/iio/adc/Makefile                      |    1 +
>  drivers/iio/adc/mcp3564.c                     | 1541 +++++++++++++++++
>  6 files changed, 1815 insertions(+)
>  create mode 100644 Documentation/ABI/testing/sysfs-bus-iio-adc-mcp3564
>  create mode 100644 Documentation/devicetree/bindings/iio/adc/microchip,mcp3564.yaml
>  create mode 100644 drivers/iio/adc/mcp3564.c
> 
> 
> base-commit: 9e66fb52449538406cea43e9f3889c391350e76e