From: Grant Likely <grant.likely@linaro.org>
To: Alexander Holler <holler@ahsoftware.de>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
Jon Loeliger <jdl@jdl.com>, Russell King <linux@arm.linux.org.uk>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Rob Herring <robh+dt@kernel.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [RFC PATCH 5/9] dt: deps: register drivers based on the initialization order based on DT
Date: Wed, 14 May 2014 20:32:50 +0100 [thread overview]
Message-ID: <CACxGe6tThM_0+Kvo62_AEN5D_5E0GDpwowMZC4Nq=oqAZ57RxA@mail.gmail.com> (raw)
In-Reply-To: <53738496.2070800@ahsoftware.de>
On Wed, May 14, 2014 at 3:58 PM, Alexander Holler <holler@ahsoftware.de> wrote:
> Am 14.05.2014 16:13, schrieb Grant Likely:
>
>> On Mon, 12 May 2014 18:47:56 +0200, Alexander Holler
>> <holler@ahsoftware.de> wrote:
>>>
>>> The init system currently calls unknown functions with almost unknown
>>> functionality in an almost random order.
>>
>>
>> Correct, we've got a module system. Some would say that is a strength!
>> :-) That said, I don't object to optimizing to the optimal order when
>> possible.
>
>
> Modules do work after init happened, that isn't what this feature is about.
Oops, I meant modular. I wasn't talking about modules either. The
driver model is designed to match devices with drivers regardless of
the order that either of them get registered to the system. I think
that is a strong aspect of the drivercore. What it doesn't have is any
way of optimizing the probe order, which is at the heart of your
proposal.
>
>
>>
>>> Fixing this is on a short-term basis is a bit tricky.
>>>
>>> In order to register drivers with a deterministic order, a list of all
>>> available in-kernel drivers is needed. Unfortunately such a list doesn't
>>> exist, just a list of initcalls does exist.
>>>
>>> The trick now is to first call special annotated initcalls (I call those
>>> "well done") for platform drivers, but not actualy starting those drivers
>>> by calling their probe function, but just collectiong their meta datas
>>> (struct platform_driver). After all those informations were collected,
>>> available the drivers will be started according to the previously
>>> determined order.
>>
>>
>> Why does the initcall level matter? Why not just let the initcalls
>> happen, capture the calls that register a driver, and then use that list
>> later?
>
>
> Some initcalls assume that stuff is present when they called probe or
> register and do further action based on the rc code.
What I mean is that manipulating the initcall level isn't the best way
to handle it. We've got enough initcalls and there isn't a need to add
more. Other ways to handle the problem would be to either have a
variant of the platform_driver_register() that triggers your desired
behavour, or add a flag to the struct device_driver that tells the
driver core that it should try to resolve ordering. In both cases the
module_platform_driver() macro can do the magic bit. Other drivers
will have to do it manually.
g.
next prev parent reply other threads:[~2014-05-14 19:33 UTC|newest]
Thread overview: 88+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-12 16:47 [RFC PATCH 0/9] dt: dependencies (for deterministic driver initialization order based on the DT) Alexander Holler
2014-05-12 16:47 ` [RFC PATCH 1/9] dt: deps: dtc: Automatically add new property 'dependencies' which contains a list of referenced phandles Alexander Holler
2014-05-17 12:16 ` Tomasz Figa
2014-05-19 12:35 ` Alexander Holler
[not found] ` <CAJgR-BhRtc1XGqk-TVOrf2y_pYS+nratkPrf+OenP4SFcyK3ng@mail.gmail.com>
2014-05-19 17:26 ` Alexander Holler
2014-05-27 20:02 ` Grant Likely
2014-05-27 20:31 ` Alexander Holler
2014-05-12 16:47 ` [RFC PATCH 2/9] dt: deps: dependency based device creation Alexander Holler
2014-05-14 14:05 ` Grant Likely
2014-05-14 14:49 ` Alexander Holler
2014-05-14 17:20 ` Alexander Holler
2014-05-14 20:06 ` Grant Likely
2014-05-14 21:10 ` Alexander Holler
2014-05-16 11:00 ` Grant Likely
2014-05-18 9:53 ` Alexander Holler
2014-05-16 17:31 ` Alexander Shiyan
2014-05-14 15:51 ` Alexander Holler
2014-05-17 14:24 ` Tomasz Figa
2014-05-18 14:59 ` Grant Likely
2014-05-19 8:41 ` Alexander Holler
2014-05-12 16:47 ` [RFC PATCH 3/9] dt: deps: dtc: Add option to print initialization order Alexander Holler
[not found] ` <CAJgR-BhnFngGr9qxa7NvF7GExiCAr1=HS16AtN20uj7nCmLcKQ@mail.gmail.com>
2014-05-12 22:58 ` Alexander Holler
2014-05-12 16:47 ` [RFC PATCH 4/9] dt: deps: dtc: Add option to print dependency graph as dot (Graphviz) Alexander Holler
2014-05-12 16:47 ` [RFC PATCH 5/9] dt: deps: register drivers based on the initialization order based on DT Alexander Holler
2014-05-14 14:13 ` Grant Likely
2014-05-14 14:58 ` Alexander Holler
2014-05-14 19:32 ` Grant Likely [this message]
2014-05-12 16:47 ` [RFC PATCH 6/9] dt: deps: WIP: well done drivers Alexander Holler
2014-05-12 16:47 ` [RFC PATCH 7/9] dt: deps: kirkwood: make it possible to use CONFIG_OF_DEPENDENCIES Alexander Holler
2014-05-12 16:47 ` [RFC PATCH 8/9] dt: deps: dts: kirkwood: dockstar: add dependency ehci -> usb power regulator Alexander Holler
2014-05-12 16:48 ` [RFC PATCH 9/9] dt: deps: omap2: make it possible to use CONFIG_OF_DEPENDENCIES Alexander Holler
2014-05-13 15:40 ` [PATCH 10/9] dt: deps: fix bug not registering late drivers when OF_DEPENDENCIES is disabled Alexander Holler
2014-05-13 19:27 ` [RFC PATCH 11/9] dt: deps: dtc: introduce new (virtual) property no-dependencies Alexander Holler
2014-05-14 8:20 ` dt: deps: some tips about how to debug/evaluate this feature Alexander Holler
2014-05-14 14:19 ` [RFC PATCH 0/9] dt: dependencies (for deterministic driver initialization order based on the DT) Grant Likely
2014-05-14 15:02 ` Alexander Holler
2014-05-14 16:05 ` Grant Likely
2014-05-14 16:23 ` Alexander Holler
2014-05-14 17:30 ` Rob Herring
2014-05-14 17:45 ` Alexander Holler
2014-05-14 17:53 ` Alexander Holler
2014-05-14 18:16 ` Alexander Holler
2014-05-14 19:13 ` Alexander Holler
2014-05-14 19:06 ` Rob Herring
2014-05-14 19:24 ` Alexander Holler
2014-05-15 1:46 ` Alexander Holler
2014-05-14 23:00 ` Alexander Holler
2014-08-21 14:02 ` Thierry Reding
2014-08-21 19:19 ` Alexander Holler
2014-08-22 13:19 ` Mark Rutland
2014-08-22 15:45 ` Alexander Holler
2014-08-25 9:39 ` Thierry Reding
2014-08-25 13:08 ` Jon Loeliger
2014-08-25 13:37 ` Thierry Reding
2014-08-25 14:13 ` Jon Loeliger
2014-08-25 14:41 ` Thierry Reding
2014-08-26 8:42 ` Grant Likely
2014-08-26 8:49 ` Thierry Reding
2014-08-26 9:42 ` Alexander Holler
2014-08-26 10:11 ` Mark Rutland
2014-08-26 10:24 ` Thierry Reding
2014-08-27 10:34 ` Grant Likely
2014-08-27 14:44 ` Catalin Marinas
2014-08-27 16:22 ` Stephen Warren
2014-08-27 16:30 ` Alexander Holler
2014-08-27 16:37 ` Stephen Warren
2014-08-27 16:58 ` Alexander Holler
2014-08-27 17:52 ` Catalin Marinas
2014-08-27 18:14 ` Alexander Holler
2014-08-28 6:50 ` Alexander Holler
2014-08-28 9:23 ` Catalin Marinas
2014-08-29 1:43 ` Alexander Holler
2014-08-26 10:25 ` Thierry Reding
2014-08-26 10:44 ` Alexander Holler
2014-08-26 11:01 ` Alexander Holler
2014-08-26 11:08 ` Thierry Reding
2014-08-26 11:23 ` Alexander Holler
2014-08-26 11:47 ` Thierry Reding
2014-08-26 12:00 ` Alexander Holler
2014-08-26 13:58 ` Jon Loeliger
2014-08-26 14:17 ` Thierry Reding
2014-08-27 7:16 ` Alexander Holler
2014-08-27 9:26 ` Alexander Holler
2014-08-26 7:56 ` Alexander Holler
2014-08-26 8:51 ` Grant Likely
2014-08-26 9:56 ` Alexander Holler
2014-08-26 10:18 ` Alexander Holler
2014-08-26 9:54 ` Mark Rutland
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