Hi Guenter,



On 21 May 2015 at 23:59, Guenter Roeck [off-list ref] wrote:

On Thu, May 21, 2015 at 11:46:53PM +0800, Fu Wei wrote:

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Hi Guenter,

[ ... ]

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+
+       /*
+        * 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)
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