Re: [PATCH v5 2/5] gpiolib: Add support for GPIO line table lookup

From: Linus Walleij <linus.walleij@linaro.org>
To: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Harish Jenny K N <harish_kandiga@mentor.com>,
	Eugeniu Rosca <erosca@de.adit-jv.com>,
	Alexander Graf <graf@amazon.com>,
	Peter Maydell <peter.maydell@linaro.org>,
	Paolo Bonzini <pbonzini@redhat.com>,
	Phil Reid <preid@electromag.com.au>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Christoffer Dall <christoffer.dall@arm.com>,
	Magnus Damm <magnus.damm@gmail.com>,
	Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	Linux Doc Mailing List <linux-doc@vger.kernel.org>,
	Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	QEMU Developers <qemu-devel@nongnu.org>
Subject: Re: [PATCH v5 2/5] gpiolib: Add support for GPIO line table lookup
Date: Thu, 12 Mar 2020 15:21:34 +0100	[thread overview]
Message-ID: <CACRpkda1JAnC=Feb39GeKEEP6q8Qwpsth6J+4OKj6A8S3YAUyQ@mail.gmail.com> (raw)
In-Reply-To: <20200218151812.7816-3-geert+renesas@glider.be>

Hi Geert,

I'm sorry for the slow review, it's a large patch set and
takes some time to sit down and review, and see whether my
earlier comments have been addressed.

On Tue, Feb 18, 2020 at 4:18 PM Geert Uytterhoeven
<geert+renesas@glider.be> wrote:

> Currently GPIOs can only be referred to by GPIO controller and offset in
> GPIO lookup tables.
>
> Add support for looking them up by line name.
> Rename gpiod_lookup.chip_label to gpiod_lookup.key, to make it clear
> that this field can have two meanings, and update the kerneldoc and
> GPIO_LOOKUP*() macros.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> Reviewed-by: Ulrich Hecht <uli+renesas@fpond.eu>
> Reviewed-by: Eugeniu Rosca <erosca@de.adit-jv.com>
> Tested-by: Eugeniu Rosca <erosca@de.adit-jv.com>

I will try to understand why this change is necessary to implement
the gpio aggregator (probablt I will comment that on the other
patches like "aha now I see it" or so, but it would help a lot if the
commit message
would state the technical reason to why we need to do this change,
like what it is that you want to do and why you cannot do it without
this change.

Yours,
Linus Walleij