linux-kernel - Re: [PATCH v10 6/8] iio: adc: Support ROHM BD79124 ADC

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Message-ID: <591e09b5-f446-497d-ba3b-c235dba87e6a@gmail.com>
Date: Mon, 31 Mar 2025 09:33:14 +0300
From: Matti Vaittinen <mazziesaccount@...il.com>
To: Jonathan Cameron <jic23@...nel.org>,
 Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Matti Vaittinen <matti.vaittinen@...rohmeurope.com>,
 Lars-Peter Clausen <lars@...afoo.de>, Nuno Sa <nuno.sa@...log.com>,
 David Lechner <dlechner@...libre.com>,
 Javier Carrasco <javier.carrasco.cruz@...il.com>,
 Olivier Moysan <olivier.moysan@...s.st.com>,
 Guillaume Stols <gstols@...libre.com>,
 Dumitru Ceclan <mitrutzceclan@...il.com>,
 Trevor Gamblin <tgamblin@...libre.com>,
 Matteo Martelli <matteomartelli3@...il.com>,
 Alisa-Dariana Roman <alisadariana@...il.com>,
 João Paulo Gonçalves <joao.goncalves@...adex.com>,
 AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
 linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org
Subject: Re: [PATCH v10 6/8] iio: adc: Support ROHM BD79124 ADC

On 30/03/2025 19:35, Jonathan Cameron wrote:
> On Mon, 24 Mar 2025 10:23:52 +0200
> Andy Shevchenko <andriy.shevchenko@...ux.intel.com> wrote:
> 
>> On Mon, Mar 24, 2025 at 09:13:42AM +0200, Matti Vaittinen wrote:
>>> The ROHM BD79124 is a 12-bit, 8-channel, SAR ADC. The ADC supports
>>> an automatic measurement mode, with an alarm interrupt for out-of-window
>>> measurements. The window is configurable for each channel.
>>>
>>> The I2C protocol for manual start of the measurement and data reading is
>>> somewhat peculiar. It requires the master to do clock stretching after
>>> sending the I2C slave-address until the slave has captured the data.
>>> Needless to say this is not well suopported by the I2C controllers.
>>>
>>> Thus do not support the BD79124's manual measurement mode but implement
>>> the measurements using automatic measurement mode, relying on the
>>> BD79124's ability of storing latest measurements into register.
>>>
>>> Support also configuring the threshold events for detecting the
>>> out-of-window events.
>>>
>>> The BD79124 keeps asserting IRQ for as long as the measured voltage is
>>> out of the configured window. Thus, prevent the user-space from choking
>>> on the events and mask the received event for a fixed duration (1 second)
>>> when an event is handled.
>>>
>>> The ADC input pins can be also configured as general purpose outputs.
>>> Make those pins which don't have corresponding ADC channel node in the
>>> device-tree controllable as GPO.
>>
>> Thank you for the nicely written driver!
>> However, I have one big issue with it (see below).
>>
>> ...
>>
>>> +static void bd79124gpo_set(struct gpio_chip *gc, unsigned int offset, int value)
>>> +static void bd79124gpo_set_multiple(struct gpio_chip *gc, unsigned long *mask,
>>> +				    unsigned long *bits)
>>
>> These will be _rv variants anyway as there is no chance this series goes before that.
> 
> I don't mind seeing this as a follow up series, but I would like that
> to hit this cycle if possible.

Should be possible :) I think the use of _rv will nicely tidy-up the 
set_multiple. I'll cook a patch when rc1 is out - or when IIO has the 
_rv variants in a branch where I can base the changes.

Yours,
	-- Matti