tegra3 vSMP cpu hotplug and LP=>G & G=>LP switch

[Barry Song]

2012/1/30 Olof Johansson <olof at lixom.net>:
> On Sat, Jan 28, 2012 at 6:58 AM, Barry Song <21cnbao at gmail.com> wrote:
>> hi guys,
>> As tegra3 is using vSMP (Variable Symmetric Multiprocessing) arch,
>> there are 4 high-performance(G) cores and one low-power(LP) core. At
>> runtime, both cpu dynamic hotplug and dynamic LP/G swith are used in a
>> real tegra3 product as a DVFS way to save power. kernel log in EeePad:
>> *cpu dynamic hotplug*
>> <4>[104626.426957] CPU1: Booted secondary processor
>> <7>[104627.427412] tegra CPU: force EDP limit 720000 kHz
>> <4>[104627.427670] CPU2: Booted secondary processor
>> <4>[104628.537005] stop_machine_cpu_stop cpu=0
>> <4>[104628.537017] stop_machine_cpu_stop cpu=2
>> <4>[104628.537059] stop_machine_cpu_stop cpu=1
>> <4>[104628.537702] __stop_cpus: wait_for_completion_timeout+
>> <4>[104628.537810] __stop_cpus: smp=0 done.executed=1 done.ret =0-
>> <5>[104628.537960] CPU1: clean shutdown
>> <4>[104630.537092] stop_machine_cpu_stop cpu=0
>> <4>[104630.537172] stop_machine_cpu_stop cpu=2
>> <4>[104630.537739] __stop_cpus: wait_for_completion_timeout+
>> <4>[104630.538060] __stop_cpus: smp=0 done.executed=1 done.ret =0-
>> <5>[104630.538203] CPU2: clean shutdown
>> <4>[104631.306984] tegra_watchdog_touch
>>
>> *G<->LP switch*
>> <3>[104666.799152] LP=>G: prolog 22 us, switch 2129 us, epilog 24 us,
>> total 2175 us
>> <3>[104667.807273] G=>LP: prolog 18 us, switch 157 us, epilog 25 us,
>> total 200 us
>> <4>[104671.407008] tegra_watchdog_touch
>> <4>[104671.408816] nct1008_get_temp: ret temp=35C
>> <3>[104671.939060] LP=>G: prolog 17 us, switch 2127 us, epilog 22 us,
>> total 2166 us
>> <3>[104672.938091] G=>LP: prolog 18 us, switch 156 us, epilog 24 us,
>> total 198 us
>>
>> Related codes don't exist in both http://nv-tegra.nvidia.com/gitweb
>> and kernel org, any people know the address to locate these kernel
>> source codes?
>
>
> You need to contact the manufacturer of the device to get the exact
> sources (I expect).

i guess the manufacturer of the device got these kernel codes from
Nvidia, not by themselves.

>
> That being said, from a quick glance I found code that prints out
> those messages on the freshest branch (named rel-14r7) at
> nv-tegra.nvidia.com's linux-2.6 repo.

Olof, thanks a lot. i saw that tree before, but didn't grep in detail.
now i do find auto hotplug and big/little switch codes in it after you
point out.
there is something interesting in arch/arm/mach-tegra/cpu-tegra3.c and
arch/arm/mach-tegra/cpu-tegra.c but not in lkml yet.

>
>
> -Olof

-barry