linux-kernel - Re: [PATCH RESEND v3 12/17] iio: adc: ad7768-1: Add GPIO controller support

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Message-ID: <Z8DazwTguF/gfKW1@JSANTO12-L01.ad.analog.com>
Date: Thu, 27 Feb 2025 18:36:15 -0300
From: Jonathan Santos <jonath4nns@...il.com>
To: David Lechner <dlechner@...libre.com>
Cc: Linus Walleij <linus.walleij@...aro.org>,
	Jonathan Santos <Jonathan.Santos@...log.com>,
	linux-iio@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Sergiu Cuciurean <sergiu.cuciurean@...log.com>, lars@...afoo.de,
	Michael.Hennerich@...log.com, marcelo.schmitt@...log.com,
	jic23@...nel.org, robh@...nel.org, krzk+dt@...nel.org,
	conor+dt@...nel.org, marcelo.schmitt1@...il.com
Subject: Re: [PATCH RESEND v3 12/17] iio: adc: ad7768-1: Add GPIO controller
 support

On 02/20, David Lechner wrote:
> On 2/19/25 2:34 PM, Linus Walleij wrote:
> > Hi Jonathan/Sergiu,
> > 
> > thanks for your patch!
> > 
> > On Wed, Feb 12, 2025 at 7:20 PM Jonathan Santos
> > <Jonathan.Santos@...log.com> wrote:
> > 
> >> From: Sergiu Cuciurean <sergiu.cuciurean@...log.com>
> >>
> >> The AD7768-1 has the ability to control other local hardware (such as gain
> >> stages),to power down other blocks in the signal chain, or read local
> >> status signals over the SPI interface.
> >>
> >> This change exports the AD7768-1's four gpios and makes them accessible
> >> at an upper layer.
> >>
> >> Signed-off-by: Sergiu Cuciurean <sergiu.cuciurean@...log.com>
> >> Co-developed-by: Jonathan Santos <Jonathan.Santos@...log.com>
> >> Signed-off-by: Jonathan Santos <Jonathan.Santos@...log.com>
> > 
> > Is it not possible to use the gpio regmap library in this driver
> > like we do in drivers/iio/addac/stx104.c?
> > 
> > It cuts down the code size of simple GPIO chips on random
> > chips quite a lot.
> > 
> > Yours,
> > Linus Walleij
> 
> I think the answer is "no" since we need to hold a conditional lock
> while accessing registers. Namely: iio_device_claim_direct_mode()/
> iio_device_release_direct_mode().
> 
> Unless we add some extra stuff to the gpio regmap implementation to
> add optional callbacks to call these. Which could be worth it given
> that quite a few ADCs provide GPIOs like this.

Since this patch set is quite large already, is it worth to do this
here? if you say it is necessary, i can try this.

>