linux-kernel - Re: [PATCH 04/13] pinctrl: tegra: Only set the gpio range if needed

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Date:	Wed, 15 Jul 2015 10:13:40 +0200
From:	Tomeu Vizoso <tomeu.vizoso@...labora.com>
To:	Alexandre Courbot <gnurou@...il.com>
Cc:	Linus Walleij <linus.walleij@...aro.org>,
	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...il.com>,
	Mark Rutland <mark.rutland@....com>,
	Krzysztof Kozlowski <k.kozlowski@...sung.com>,
	Andrzej Hajda <a.hajda@...sung.com>,
	Lv Zheng <lv.zheng@...el.com>,
	Alexander Holler <holler@...oftware.de>,
	Russell King <linux@....linux.org.uk>,
	Arnd Bergmann <arnd@...db.de>,
	Robert Moore <robert.moore@...el.com>,
	Grant Likely <grant.likely@...aro.org>,
	Len Brown <lenb@...nel.org>, Pawel Moll <pawel.moll@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Rob Herring <robh+dt@...nel.org>,
	Terje Bergström <tbergstrom@...dia.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Mark Brown <broonie@...nel.org>,
	Kumar Gala <galak@...eaurora.org>
Subject: Re: [PATCH 04/13] pinctrl: tegra: Only set the gpio range if needed

On 15 July 2015 at 05:17, Alexandre Courbot <gnurou@...il.com> wrote:
> On Tue, Jul 14, 2015 at 5:34 PM, Tomeu Vizoso
> <tomeu.vizoso@...labora.com> wrote:
>> On 13 July 2015 at 22:14, Linus Walleij <linus.walleij@...aro.org> wrote:
>>> On Wed, Jun 17, 2015 at 3:42 PM, Tomeu Vizoso
>>> <tomeu.vizoso@...labora.com> wrote:
>>>
>>>> If the gpio DT node has the gpio-ranges property, the range will be
>>>> added by the gpio core and doesn't need to be added by the pinctrl
>>>> driver.
>>>>
>>>> By having the gpio-ranges property, we have an explicit dependency from
>>>> the gpio node to the pinctrl node and we can stop using the deprecated
>>>> pinctrl_add_gpio_range() function.
>>>>
>>>> Note that when the GPIO device gets probed before the associated
>>>> princtrl device, the gpio core actually won't register the gpio range.
>>>> Thus, this patch is only safe to be merged after we have in place a way
>>>> to assure that gpio devices are probed after their associated pinctrl
>>>> devices (such as ordered probing).
>>>>
>>>> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@...labora.com>
>>>
>>> This doesn't look like it would hurt, but need Stephen's opinion
>>> on it, and I think he's on vacation. Would check with next-in-line
>>> Tegra maintainer, Thierry/Alexandre?
>>
>> Sorry about that, but I have split these changes out into their own
>> series after people complained about it.
>>
>> Have just sent a new version which already has Stephen's ack:
>>
>> https://lkml.kernel.org/g/1436862596-27730-1-git-send-email-tomeu.vizoso@collabora.com
>
> The change looks ok, but why limit it to Tegra? It seems like it could
> apply to any driver that supports gpio-range. Or is it because this
> will only work with drivers that use ordered probing?

It has to be SoC specific because we need to find out if a node
representing the in-SoC gpio controller is present, and has the
gpio-ranges property.

I guess we could move the code to the pinctrl core and parametrize the
property name but given that pinctrl_add_gpio_range is deprecated and
that we are doing this only for DT compatibility, I'm not sure it
would be a good idea.

Regards,

Tomeu
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