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From: "Andrew Jeffery" <andrew@aj.id.au>
To: "Linus Walleij" <linus.walleij@linaro.org>
Cc: "Linux LED Subsystem" <linux-leds@vger.kernel.org>,
	"open list:GPIO SUBSYSTEM" <linux-gpio@vger.kernel.org>,
	"Cédric Le Goater" <clg@kaod.org>,
	"Rob Herring" <robh+dt@kernel.org>,
	"Joel Stanley" <joel@jms.id.au>, "Pavel Machek" <pavel@ucw.cz>,
	"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
	<devicetree@vger.kernel.org>,
	"Linux ARM" <linux-arm-kernel@lists.infradead.org>,
	linux-aspeed <linux-aspeed@lists.ozlabs.org>,
	linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH 4/6] leds: pca955x: Use pinctrl to map GPIOs to pins
Date: Wed, 11 Aug 2021 09:49:05 +0930	[thread overview]
Message-ID: <96e52916-f113-4a91-b83f-e0de144611ca@www.fastmail.com> (raw)
In-Reply-To: <CACRpkdZm9C23aHTWs8DNX1RChSB4A-X0PoyW5wnH2XyQQeviag@mail.gmail.com>



On Tue, 10 Aug 2021, at 23:24, Linus Walleij wrote:
> On Fri, Jul 23, 2021 at 9:59 AM Andrew Jeffery <andrew@aj.id.au> wrote:
> 
> > The leds-pca955x driver currently assumes that the GPIO numberspace and
> > the pin numberspace are the same. This quickly falls apart with a
> > devicetree binding such as the following:
> (...)
> 
> Honestly I do not understand this patch. It seems to implement a pin
> controller and using it in nonstandard ways.

Yeah, it's a bit abusive, hence RFC :)

> 
> If something implements the pin controller driver API it should be
> used as such IMO, externally. This seems to be using it do relay
> calls to itself which seems complicated, just invent something
> locally in the driver in that case? No need to use pin control?

Right. After discussions with Andy I'm going to rework the approach to 
GPIOs which will remove a lot of complexity.

The thought was to try to maintain the intent of the devicetree binding 
and use existing APIs, but all-in-all it's ended up twisting things up 
in knots a fair bit. We discard a lot of it by making the gpiochip 
always cover all pins and track use directly in the driver.

> 
> Can you explain why this LED driver needs to implement a pin
> controller?

The short answer is it doesn't as it has none of the associated 
hardware.

I'll cook up something simpler with the aim to avoid non-standard (or 
any) pinctrl.

Andrew

  reply	other threads:[~2021-08-11  0:19 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-23  7:58 [RFC PATCH 0/6] leds: Fix pca955x GPIO pin mappings Andrew Jeffery
2021-07-23  7:58 ` [RFC PATCH 1/6] pinctrl: Add pinctrl_gpio_as_pin() Andrew Jeffery
2021-08-10 13:34   ` Linus Walleij
2021-08-11  0:24     ` Andrew Jeffery
2021-07-23  7:58 ` [RFC PATCH 2/6] pinctrl: Add hook for device-specific map parsing Andrew Jeffery
2021-07-23  7:58 ` [RFC PATCH 3/6] leds: pca955x: Relocate chipdef-related descriptors Andrew Jeffery
2021-07-23  7:58 ` [RFC PATCH 4/6] leds: pca955x: Use pinctrl to map GPIOs to pins Andrew Jeffery
2021-08-10 13:54   ` Linus Walleij
2021-08-11  0:19     ` Andrew Jeffery [this message]
2021-07-23  7:58 ` [RFC PATCH 5/6] ARM: dts: rainier: Add presence-detect and fault indictor GPIO expander Andrew Jeffery
2021-07-23  7:58 ` [RFC PATCH 6/6] pinctrl: Check get_group_pins callback on init Andrew Jeffery
     [not found] ` <CAHp75VeQML7njMZ6x8kC-ZJVexC1xJ6n1cB3JneVMAVfuOJgWw@mail.gmail.com>
2021-07-28  5:43   ` [RFC PATCH 0/6] leds: Fix pca955x GPIO pin mappings Andrew Jeffery
2021-07-28  9:13     ` Andy Shevchenko
2021-07-29  0:38       ` Andrew Jeffery
2021-07-29  7:40         ` Andy Shevchenko
2021-08-03  4:07           ` Andrew Jeffery
2021-08-03 10:33             ` Andy Shevchenko
2021-08-04  4:55               ` Andrew Jeffery

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