linux-kernel - Re: [PATCH 1/3] driver core: Add API to wait for deferred probe to complete during init

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Date:	Thu, 09 May 2013 11:12:24 -0700
From:	Saravana Kannan <skannan@...eaurora.org>
To:	Grant Likely <grant.likely@...retlab.ca>
CC:	Ming Lei <tom.leiming@...il.com>,
	Mike Turquette <mturquette@...aro.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Stephen Boyd <sboyd@...eaurora.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	"linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
	Liam Girdwood <lrg@...com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH 1/3] driver core: Add API to wait for deferred probe to
 complete during init

On 05/09/2013 11:09 AM, Grant Likely wrote:
> On Thu, May 9, 2013 at 5:52 PM, Saravana Kannan <skannan@...eaurora.org> wrote:
>> On 05/09/2013 04:50 AM, Grant Likely wrote:
>>>
>>> On Thu, May 9, 2013 at 11:07 AM, Ming Lei <tom.leiming@...il.com> wrote:
>>>>
>>>> On Thu, May 9, 2013 at 1:18 PM, Saravana Kannan <skannan@...eaurora.org>
>>>> wrote:
>>>>>
>>>>>
>>>>> The most obvious fallback of using late_initcall_sync() also doesn't
>>>>> work
>>>>> since the deferred probing work initated during late_initcall() is done
>>>>> in
>>>>> a workqueue. So, frameworks that want to wait for all devices to finish
>>>>> probing during init will now have to wait for the deferred workqueue to
>>>>> finish it's work. This patch adds a wait_for_init_deferred_probe_done()
>>>>> API
>>>>
>>>>
>>>> flush_workqueue() has been added in deferred_probe_initcall(), so looks
>>>> it
>>>> should be OK for your problem, doesn't it?
>>>
>>>
>>> It looks like Saravana is using a kernel that already does that based
>>> on object bb5645e from the diff. So if he is still having problem,
>>> then there is probably another deferred probe that is triggered after
>>> the deferred probe lateinitcall is executed. It would be good to know
>>> what driver is getting deferred past clearing the queue. Or has this
>>> been rebased from an earlier kernel? It may no longer be necessary.
>>
>>
>> Sorry, it was mindless rebase late at night. I missed the addition of the
>> flush_workqueue(). That takes care of my immediate needs. Sorry for wasting
>> your time.
>>
>> But the other patches to move clock and regulator calls to late_init_sync
>> should still be necessary. Right? Or are we going to depend on the Makefile
>> ordering to determine the order of the lateinit calls? (I would rather not).
>
> You'll need to make sure the regulator and clocks defer to after all
> the late initcalls are complete. That will ensure that the deferred
> queue has been processed.
>

Ok, then I guess I'll still need to send out the other 2 patches.

-Saravana

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