linux-kernel - RE: [PATCH 2/2] gpio: gpio-adg1414: New driver

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Date: Wed, 24 Jan 2024 03:44:58 +0000
From: "Paller, Kim Seer" <KimSeer.Paller@...log.com>
To: Linus Walleij <linus.walleij@...aro.org>
CC: Bartosz Golaszewski <brgl@...ev.pl>,
        "linux-gpio@...r.kernel.org"
	<linux-gpio@...r.kernel.org>,
        "devicetree@...r.kernel.org"
	<devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof
 Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley
	<conor+dt@...nel.org>
Subject: RE: [PATCH 2/2] gpio: gpio-adg1414: New driver

> -----Original Message-----
> From: Linus Walleij <linus.walleij@...aro.org>
> Sent: Wednesday, January 24, 2024 5:51 AM
> To: Paller, Kim Seer <KimSeer.Paller@...log.com>
> Cc: Bartosz Golaszewski <brgl@...ev.pl>; linux-gpio@...r.kernel.org;
> devicetree@...r.kernel.org; linux-kernel@...r.kernel.org; Rob Herring
> <robh+dt@...nel.org>; Krzysztof Kozlowski
> <krzysztof.kozlowski+dt@...aro.org>; Conor Dooley <conor+dt@...nel.org>
> Subject: Re: [PATCH 2/2] gpio: gpio-adg1414: New driver
> 
> [External]
> 
> Hi Kim,
> 
> On Tue, Jan 23, 2024 at 11:31 AM Paller, Kim Seer
> <KimSeer.Paller@...log.com> wrote:
> 
> > > Locking here is simple enough that you could use the SPI regmap and
> > > get it to do the serialization for you. And then you could possibly
> > > reuse the gpio-regmap abstraction and get an even smaller footprint.
> >
> > I could not seem to figure out how to use the SPI regmap in this case.
> > Since the number of daisy-chained devices depends on the length of
> > data transferred with continuous transaction, I could not determine
> > how to implement that using the SPI regmap. Or maybe I misunderstood
> > the statement. However, is it still acceptable to use the current approach?
> 
> You just override or wrap with your own read/write callbacks if necessary
> by defining a custom static struct regmap_bus.
> 
> For example in drivers/gpu/drm/panel/panel-ilitek-ili9322.c
> I do this.
> 
> It may not save a lot of code in this case but it's still worth it because
> we understand what regmap_read/write/update_bits do and reading
> and understanding adg1414_set/get cognitively require more from us
> as maintainers.

Hi Linus,

I'll check this out.

Thanks,
Kim