Problems booting exynos5420 with >1 CPU

[Nicolas Pitre]

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