linux-kernel - Re: [PATCH 1/2] ARM: simplify timer initialisation and remove arm

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Message-ID: <5559C288.7020703@arm.com>
Date:	Mon, 18 May 2015 11:44:24 +0100
From:	Sudeep Holla <sudeep.holla@....com>
To:	Russell King - ARM Linux <linux@....linux.org.uk>
CC:	Sudeep Holla <sudeep.holla@....com>, Rob Herring <robh@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Catalin Marinas <Catalin.Marinas@....com>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Arnd Bergmann <arnd@...db.de>, Olof Johansson <olof@...om.net>
Subject: Re: [PATCH 1/2] ARM: simplify timer initialisation and remove arm_timer.h
 inclusion


On 18/05/15 11:42, Russell King - ARM Linux wrote:
> On Thu, Apr 30, 2015 at 03:19:01PM +0100, Sudeep Holla wrote:
>>
>>
>> On 30/04/15 15:09, Rob Herring wrote:
>>> On Thu, Apr 30, 2015 at 5:44 AM, Sudeep Holla <sudeep.holla@....com> wrote:
>>>> The header asm/hardware/arm_timer.h is included in various machine
>>>> specific files to access TIMER_CTRL and initialise to a known state.
>>>> However that's not required as the clock{source,event} driver timer-sp
>>>> initialises all the timer being used.
>>>
>>> I believe the idea is not to initialize the timers being used, but the
>>> ones not being used and perhaps left running by the bootloader. Cases
>>> where the interrupt is shared could cause a problem.
>>>
>>
>> Ah OK, makes sense. I will wait for Russell to confirm. The main idea
>> was to keep the header file having offsets local to driver/clocksource
>> and avoid sharing it in include/linux but looks like that's not possible.
>
> An alternative would be to have a new function, something like
> sp804_disable() which takes the virtual address of the timer.
> That'd still allow the platforms to disable all timers, but
> without exposing the register stuff to them.
>

Yes that's much better, will re-spin the patch accordingly.

Regards,
Sudeep
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