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

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Date:	Thu, 21 May 2015 11:33:01 -0500
From:	Timur Tabi <timur@...eaurora.org>
To:	Fu Wei <fu.wei@...aro.org>, 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>,
	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

On 05/21/2015 11:12 AM, Fu Wei wrote:
>> >
>> >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

The rate isn't the problem.  It's the current timestamp counter.  The 
only way to get that is with either arch_counter_get_cntvct() or 
arch_timer_read_counter().  I'm not sure which of the two functions is 
better.  However, arch_timer_read_counter() is really just a function 
pointer that points to arch_counter_get_cntvct().

Also, clk_get_rate() only works if you have a real clk object.  I've 
said this before many times, but on my ACPI platform, there are no clk 
objects.  Clocks are handled by UEFI.

-- 
Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the
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