linux-kernel - Re: [PATCH v2 6/7] Watchdog: introduce ARM SBSA watchdog driver

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Message-ID: <CADyBb7vwGcdxeOE+QEzgmF5=2dsk83F4WyfJvp2ccZ12w1qYHQ@mail.gmail.com>
Date:	Fri, 22 May 2015 00:12:21 +0800
From:	Fu Wei <fu.wei@...aro.org>
To:	Guenter Roeck <linux@...ck-us.net>
Cc:	Suravee Suthikulpanit <Suravee.Suthikulpanit@....com>,
	Linaro ACPI Mailman List <linaro-acpi@...ts.linaro.org>,
	linux-watchdog@...r.kernel.org, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
	Wei Fu <tekkamanninja@...il.com>,
	G Gregory <graeme.gregory@...aro.org>,
	Al Stone <al.stone@...aro.org>,
	Hanjun Guo <hanjun.guo@...aro.org>,
	Timur Tabi <timur@...eaurora.org>,
	Ashwin Chaugule <ashwin.chaugule@...aro.org>,
	Arnd Bergmann <arnd@...db.de>, vgandhi@...eaurora.org,
	wim@...ana.be, Jon Masters <jcm@...hat.com>,
	Leo Duran <leo.duran@....com>, Jon Corbet <corbet@....net>,
	Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH v2 6/7] Watchdog: introduce ARM SBSA watchdog driver

Hi Guenter,



On 21 May 2015 at 23:59, Guenter Roeck <linux@...ck-us.net> wrote:
> On Thu, May 21, 2015 at 11:46:53PM +0800, Fu Wei wrote:
>> Hi Guenter,
>>
> [ ... ]
>
>> >> >> +
>> >> >> +       /*
>> >> >> +        * Try to determine the frequency from the arch_timer interface
>> >> >> +        */
>> >> >> +       clk = arch_timer_get_rate();
>> >> >
>> >> >
>> >> > arch_timer_get_rate() does not seem to be exported. Did you try to build
>> >> > the driver as module ?
>> >>
>> >> yes, I have built it as a ko module, that is why I made a patch to
>> >> export this interface in the first patch of this patchset
>> >>
>> >>  but I will confirm it again :-)
>> >>
>> > Guess I'll give it a try myself. I don't really understand how this
>> > can work unless arch_timer_get_rate() is exported in your tree.
>>
>> yes, I have exported it , I think it make sense to export it.
>> Because other driver maybe need to get system counter info
>>
>> Do you agree ? :-)
>>
> I don't think it is for me to agree or not. The arm maintainers
> will need to be involved. You can not just export such a function
> without maintainer Ack.

yes, I have added Mark Rutland in the CC list when I sent this
patchset . He added the "arch_timer_get_rate();" in the arch timer
driver.
See if he can provide some suggestion. :-)

maybe I should add some more arm arch timer maintainers to get more
help on this :-)

>
> Having said that, my personal preference would be for the counter
> and rate to be exported through the clock subsystem (ie with
> clk_get_rate). But that would still not provide the current counter
> value, so maybe that isn't even possible.

I will try to make a patch for this, If the arm maintainers don't like
exporting "arch_timer_get_rate();"

But your thought is good,  the clk_get_rate is the best way to do for now

>
> Thanks,
> Guenter



-- 
Best regards,

Fu Wei
Software Engineer
Red Hat Software (Beijing) Co.,Ltd.Shanghai Branch
Ph: +86 21 61221326(direct)
Ph: +86 186 2020 4684 (mobile)
Room 1512, Regus One Corporate Avenue,Level 15,
One Corporate Avenue,222 Hubin Road,Huangpu District,
Shanghai,China 200021
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