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From: Linus Walleij <linus.walleij-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
To: Grant Likely <grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
Cc: "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org"
	<linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org>,
	Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>,
	Lee Jones <lee.jones-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
	Bryan Wu <cooloney-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>,
	Catalin Marinas <catalin.marinas-5wv7dgnIgG8@public.gmane.org>,
	Will Deacon <will.deacon-5wv7dgnIgG8@public.gmane.org>,
	Richard Purdie <rpurdie-Fm38FmjxZ/leoWH0uzbU5w@public.gmane.org>,
	Devicetree <devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	Rob Herring <robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Benjamin Herrenschmidt
	<benh-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>,
	Pawel Moll <pawel.moll-5wv7dgnIgG8@public.gmane.org>,
	Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org>,
	Ian Campbell
	<ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org>,
	Kumar Gala <galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org>
Subject: Re: [PATCH 1/5] MFD/OF: document MFD devices and handle simple-mfd
Date: Tue, 7 Apr 2015 11:03:31 +0200	[thread overview]
Message-ID: <CACRpkdYC_xG90bqnsog_C67WfBi1bcwki1DeN_jozmu5RTW89w@mail.gmail.com> (raw)
In-Reply-To: <20150328134157.000A3C40AE0-WNowdnHR2B42iJbIjFUEsiwD8/FfD2ys@public.gmane.org>

On Sat, Mar 28, 2015 at 2:41 PM, Grant Likely <grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org> wrote:

> However, I think this is going to lead to a future problem. It solves
> the immediate case of getting an MFD device to be auto populated when
> the kernel doesn't need to immediately do something. However, I can
> forsee a situation where the device can be supported by simple-mfd, but
> at some point it is discovered that better features can be enabled if
> the mfd device has a proper driver.

For the general case where access to the MFD needs some mediation
or marshalling yes, I think this is theoretically possible.

For the most common MMIO case where the MFD devide is a syscon,
it is not so likely. Or rather extremelt unlikely.

We could restrict the use cases to strictly syscon/MMIO MFD devices
but it would just be a documentation fix.

Yours,
Linus Walleij
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WARNING: multiple messages have this Message-ID (diff)
From: linus.walleij@linaro.org (Linus Walleij)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 1/5] MFD/OF: document MFD devices and handle simple-mfd
Date: Tue, 7 Apr 2015 11:03:31 +0200	[thread overview]
Message-ID: <CACRpkdYC_xG90bqnsog_C67WfBi1bcwki1DeN_jozmu5RTW89w@mail.gmail.com> (raw)
In-Reply-To: <20150328134157.000A3C40AE0@trevor.secretlab.ca>

On Sat, Mar 28, 2015 at 2:41 PM, Grant Likely <grant.likely@linaro.org> wrote:

> However, I think this is going to lead to a future problem. It solves
> the immediate case of getting an MFD device to be auto populated when
> the kernel doesn't need to immediately do something. However, I can
> forsee a situation where the device can be supported by simple-mfd, but
> at some point it is discovered that better features can be enabled if
> the mfd device has a proper driver.

For the general case where access to the MFD needs some mediation
or marshalling yes, I think this is theoretically possible.

For the most common MMIO case where the MFD devide is a syscon,
it is not so likely. Or rather extremelt unlikely.

We could restrict the use cases to strictly syscon/MMIO MFD devices
but it would just be a documentation fix.

Yours,
Linus Walleij

  parent reply	other threads:[~2015-04-07  9:03 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-03  9:32 [PATCH 0/5] simple-mfd and syscon LEDs Linus Walleij
     [not found] ` <1425375148-4369-1-git-send-email-linus.walleij-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
2015-03-03  9:32   ` [PATCH 1/5] MFD/OF: document MFD devices and handle simple-mfd Linus Walleij
2015-03-03  9:32     ` Linus Walleij
     [not found]     ` <1425375148-4369-2-git-send-email-linus.walleij-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
2015-03-03 10:25       ` Lee Jones
2015-03-03 10:25         ` Lee Jones
2015-03-09 14:29         ` Linus Walleij
2015-03-09 14:29           ` Linus Walleij
2015-03-03 17:47       ` Rob Herring
2015-03-03 17:47         ` Rob Herring
2015-03-03 17:56         ` Lee Jones
2015-03-03 17:56           ` Lee Jones
2015-03-09 14:35         ` Linus Walleij
2015-03-09 14:35           ` Linus Walleij
2015-03-12  9:14       ` Alexandre Belloni
2015-03-12  9:14         ` Alexandre Belloni
     [not found]         ` <20150312091427.GA4329-m++hUPXGwpdeoWH0uzbU5w@public.gmane.org>
2015-03-17 10:28           ` Linus Walleij
2015-03-17 10:28             ` Linus Walleij
     [not found]             ` <CACRpkdacQ-MR+Sziu-TQXWr+1UCtBphZ5eNSWbJ2ZpCnH+o9JA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-03-17 10:38               ` Linus Walleij
2015-03-17 10:38                 ` Linus Walleij
2015-03-18 16:06       ` Alexandre Belloni
2015-03-18 16:06         ` Alexandre Belloni
2015-03-20 13:26       ` Antoine Tenart
2015-03-20 13:26         ` Antoine Tenart
2015-03-28 13:41       ` Grant Likely
2015-03-28 13:41         ` Grant Likely
     [not found]         ` <20150328134157.000A3C40AE0-WNowdnHR2B42iJbIjFUEsiwD8/FfD2ys@public.gmane.org>
2015-04-07  9:03           ` Linus Walleij [this message]
2015-04-07  9:03             ` Linus Walleij
2015-04-03 18:34       ` Olof Johansson
2015-04-03 18:34         ` Olof Johansson
     [not found]         ` <CAOesGMhz6WPweQFXfPhTO6Pz5L4Z1Si6YGiCRCiFD9B5qB9tVw-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-04-07  7:16           ` Lee Jones
2015-04-07  7:16             ` Lee Jones
2015-04-07  9:00           ` Linus Walleij
2015-04-07  9:00             ` Linus Walleij
2015-03-03  9:32 ` [PATCH 2/5] ARM: dts: update syscons to use simple-mfd Linus Walleij
2015-03-03  9:32 ` [PATCH 3/5] leds: syscon: instantiate from platform device Linus Walleij
2015-03-17 10:36   ` Linus Walleij
2015-03-24 16:50   ` Bjorn Andersson
2015-03-03  9:32 ` [PATCH 4/5] arm64: juno: Add APB registers and LEDs using syscon Linus Walleij
2015-03-04 15:57   ` Liviu Dudau
2015-03-03  9:32 ` [PATCH 5/5] arm64: add LEDs and some trigger support to defconfig Linus Walleij

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