Re: [PATCH] ARM: dts: Update arch timer node with clock frequency

[Marc Zyngier <marc.zyngier-5wv7dgnIgG8@public.gmane.org>]

On 20/09/13 05:57, Yuvaraj Kumar wrote:
> Resending it as it bounced from kernel mailing group
> 
> On Wed, Sep 18, 2013 at 3:53 PM, Mark Rutland <mark.rutland-5wv7dgnIgG8@public.gmane.org> wrote:
>> [adding lakml]
>>
>> On Wed, Sep 18, 2013 at 11:11:53AM +0100, Yuvaraj Kumar C D wrote:
>>> Without the "clock-frequency" property in arch timer node, could able
>>> to see the below crash dump.
>>
>> Why does this cause the below crash specifically? What is CNTFRQ reading
>> as?
> Return value of arch_timer_get_cntfrq() is 0
>>
>> Your firmware or bootloader should set CNTFRQ -- setting the
>> clock-frequency is a work-around for buggy firmware/bootloaders that
>> should be avoided as far as possible.
> Why kernel should depend on bootloader/firmware  to set CNTFRQ? Any
> specific reasons?

Because the kernel can't set it if running non-secure. Only secure mode
can do this (see the ARM ARM for details).

> Should'nt be indepenedent each other(kernel and bootloader/firmware)?

In my book, the firmware is responsible for setting up the platform in a
sane state. Leaving CNTFRQ in its UNKNOWN reset state is a bug, and your
firmware should program it on each CPU. Same goes for CNTVOFF, which
should be set to a common value (preferably zero).

	M.
-- 
Jazz is not dead. It just smells funny...

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