From: swarren@wwwdotorg•org (Stephen Warren)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] RFC: pinctrl: grab default handler with bus notifiers
Date: Thu, 15 Nov 2012 11:23:00 -0700 [thread overview]
Message-ID: <50A53304.6040904@wwwdotorg.org> (raw)
In-Reply-To: <CACRpkdY-tye5LNOwxQ-XrjM-x9RffAvj-tPfsFQA3ZWOY8P-Vw@mail.gmail.com>
On 11/15/2012 07:03 AM, Linus Walleij wrote:
> On Tue, Nov 13, 2012 at 7:35 AM, Mark Brown
> <broonie@opensource•wolfsonmicro.com> wrote:
>> On Mon, Nov 12, 2012 at 01:21:40PM -0700, Stephen Warren wrote:
>>> On 11/11/2012 05:22 AM, Linus Walleij wrote:
>>
>>>> Another solution that was discussed was whether to move
>>>> the default pinctrl handle and state grab to the device
>>>> core as an optional field in struct device itself, but
>>>> I'd like to first propose this less intrusive mechanism.
>>
>>> I think doing that approach makes a lot more sense; wouldn't it
>>> completely avoid the issues with deferred probe that this notifier-based
>>> method can't solve? It would also be very much in line with e.g.
>>> dev_get_regmap() - if every resource that a driver required were handled
>>> like that, then deferred probe could be significantly isolated into the
>>> driver core rather than in every driver...
>>
>> I have to say that I agree with this, notifiers seem to make life more
>> complicated for limited gain. Otherwise I guess we could enhance
>> notifiers so that they're able to trigger deferrals?
>
> OK I'll have to come up with a patch to the device core
> instead... it'll be much simpler anyway and if both of you guys
> can back it I guess Greg might be OK with it too.
I did have one thought here; how will this interact with hogs? If a
device's pinctrl configuration must be pinctrl_get()'d before the device
is probed, then a pinctrl device with hogs will never get probed because
it won't be registered to provide the pinctrl node parsing. Solutions
might include:
a) Some special case where if the pinctrl driver only can't probe due to
missing pinctrl from its own node, don't defer the probe, but defer the
pinctrl_get().
b) Separate out DT node parsing from device instantiation, so that the
driver can always parse the DT, without needing the context of a
specific pinctrl device to do so.
I haven't thought through this in any detail though.
next prev parent reply other threads:[~2012-11-15 18:23 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-11 12:22 [PATCH] RFC: pinctrl: grab default handler with bus notifiers Linus Walleij
2012-11-12 20:21 ` Stephen Warren
2012-11-13 6:35 ` Mark Brown
2012-11-15 14:03 ` Linus Walleij
2012-11-15 14:26 ` Thomas Petazzoni
2012-11-15 17:24 ` Linus Walleij
2012-11-15 18:27 ` Stephen Warren
2012-11-15 18:23 ` Stephen Warren [this message]
2012-11-16 11:36 ` Linus Walleij
2012-11-16 16:09 ` Stephen Warren
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