[PATCH] clocksource: arm_global_timer: Allow DT to specify already reset timer counter

[marc.zyngier@arm.com (Marc Zyngier)]

On 17/12/15 09:37, Jassi Brar wrote:
> On 16 December 2015 at 12:29, Daniel Lezcano <daniel.lezcano@linaro.org> wrote:
>> On 12/16/2015 05:11 AM, Jassi Brar wrote:
>>>
>>> On Tue, Dec 15, 2015 at 11:32 PM, Daniel Lezcano
>>> <daniel.lezcano@linaro.org> wrote:
>>>>
>>>> On 11/25/2015 06:24 AM, Jassi Brar wrote:
>>>>>
>>>>>
>>>>> The GT counter is common to every core in a cluster. There is a usecase
>>>>> when Linux is spawned by a 'master' firmware/OS running on some core of
>>>>> the same cluster and the GT is used by the both.
>>>>>    Linux, upon boot, resetting the GT counter is obviously fatal to the
>>>>> other OS. So provide a way for DT to tell Linux if it's running in that
>>>>> 'slave' mode and must not reset the counter.
>>>>>
>>>>> Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
>>>>
>>>>
>>>>
>>>> Hmm, I doubt that is a hardware description.
>>>>
>>> Its a regular 2core-1cluster platform. The master RTOS on cpu0
>>> maintains the lifecycle of Linux on cpu1.
>>>
>>> 'No_Counter_Reset' is not a h/w thing, I agree, but I don't know how
>>> to better convey that platform specific constraint.
>>
>>
>> May be with a kernel parameter ?
>>
> The fact, that arch-timer driver does it via DT (see commit
> 65b5732d241b8), changes anything? :)

This is a horrible, platform specific hack. I wish we could have pushed
back on this by forcing people to fix their firmware. Why can't you
simply get the firmware to *remove* the node from your device tree
altogether?

Thanks,

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