linux-kernel - Re: [PATCH v1 4/4] leds: no longer use unnamed gpios

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Message-ID: <54B66D07.8040807@schinagl.nl>
Date:	Wed, 14 Jan 2015 14:20:07 +0100
From:	Olliver Schinagl <oliver@...inagl.nl>
To:	Linus Walleij <linus.walleij@...aro.org>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>
CC:	Rob Herring <robherring2@...il.com>,
	Olliver Schinagl <oliver+list@...inagl.nl>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Alexandre Courbot <gnurou@...il.com>,
	Bryan Wu <cooloney@...il.com>,
	Richard Purdie <rpurdie@...ys.net>,
	Robin Gong <b38343@...escale.com>,
	"Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
	Aaron Lu <aaron.lu@...el.com>,
	Mika Westerberg <mika.westerberg@...ux.intel.com>,
	Grant Likely <grant.likely@...aro.org>,
	Wolfram Sang <wsa@...-dreams.de>,
	Alexander Shiyan <shc_work@...l.ru>,
	Jingoo Han <jg1.han@...sung.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
	"linux-leds@...r.kernel.org" <linux-leds@...r.kernel.org>
Subject: Re: [PATCH v1 4/4] leds: no longer use unnamed gpios


On 14-01-15 13:45, Linus Walleij wrote:
> On Thu, Jan 8, 2015 at 11:12 PM, Dmitry Torokhov
> <dmitry.torokhov@...il.com> wrote:
>> On Thu, Jan 08, 2015 at 08:40:20AM -0600, Rob Herring wrote:
>>> On Thu, Jan 8, 2015 at 2:45 AM, Olliver Schinagl <oliver@...inagl.nl> wrote:
>>>>>> --- a/drivers/leds/leds-gpio.c
>>>>>> +++ b/drivers/leds/leds-gpio.c
>>>>>> @@ -184,7 +184,7 @@ static struct gpio_leds_priv *gpio_leds_create(struct
>>>>>> platform_device *pdev)
>>>>>>                  struct gpio_led led = {};
>>>>>>                  const char *state = NULL;
>>>>>>    -             led.gpiod = devm_get_gpiod_from_child(dev, NULL, child);
>>>>>> +               led.gpiod = devm_get_gpiod_from_child(dev, "led", child);
>>>>> Would not this break existing boards using old bindings? You need to
>>>>> handle both cases: if you can't located "led-gpios" then you will have to
>>>>> try just "gpios".
>>>> Very true. I was rather even hoping we could update all bindings, I don't
>>>> mind going through the available dts files to fix them ... But need to know
>>>> that that's the proper way to go before doing the work ;)
>>> That will not work. You cannot make changes that require a new dtb
>>> with a new kernel. This would also break for the other way around
>>> (i.e. a new dtb and old kernel).
>>>
>>> You would have to search for both led-gpios and gpios. I'm not sure if
>>> we can do that generically for all GPIOs. If you had a node with both
>>> "blah-gpios" and "gpios", it would break. I would hope there are no
>>> such cases like that. We also now have to consider how ACPI identifies
>>> GPIOs and whether this makes sense.
>> I think only the driver itself can know about such "legacy" mappings and
>> make a decision.
> Yeah leds-gpio.c will need to be patched to check for "led-gpios" first
> and then fall back to "gpios" if not found.
yeah I've done the work, just need to double check it and resend a v2.

Linus, I assume you want the already applied patches omitted from v2?

Olliver
>
> Yours,
> Linus Walleij

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