Problems booting exynos5420 with >1 CPU

[Abhilash Kesavan]

Hi Nicolas,

The first man of the incoming cluster enables its snoops via the
power_up_setup function. During secondary boot-up, this does not occur
for the boot cluster. Hence, I enable the snoops for the boot cluster
as a one-time setup from the u-boot prompt. After secondary boot-up
there is no modification that I do. Where should this be ideally done
?

Regards,
Abhilash

On Sat, Jun 7, 2014 at 3:18 AM, Nicolas Pitre <nicolas.pitre at linaro.org> wrote:
> On Fri, 6 Jun 2014, Abhilash Kesavan wrote:
>
>> Hi Doug,
>>
>> The first change in the kernel (clearing an iRAM location) is needed
>> because of an unnecessary change that we are carrying in the Chrome
>> U-boot. There is no reason for us to have the workaround in the
>> mainline kernel. Rather, we should remove the check from our u-boot.
>> However AFAIR a clean-up patch that I had posted internally was not
>> accepted as we had frozen the SPL at the time.
>>
>> The second change is to enable snoops for boot cluster. Internally, we
>> were disabling the snoops for both the clusters at power off and
>> enabling it in power_up_setup and power_up. However, I dropped the
>> approach due to problems pointed out by Nicolas here
>> http://www.spinics.net/lists/arm-kernel/msg324091.html related to
>> cpuidle. Hence, we turn it on at the u-boot.
>
> You should never *ever* play with the CCI from U-Boot.  That's for the
> MCPM layer to decide when it is safe to do so.  That's mainly the
> _whole_ reason why MCPM exists in the first place.
>
>
> Nicolas