how to enable the i.MX8M SCU(snoop control unit)

[anhui527]

hi, commnity guys and NXP experts:

   we are using the i.MX8M's EVK board(MCIMX8M-EVK) to develop test application . we need to enable all four A53 cores in the u-boot stage. but  we encount some problems with the multi-core A53 uasge.

   when we assign the task to the slave core to run , the synchronus abort will occur on the slave core. we guess that this abort maybe triggered by L1-cache coherency among multi-core. so we try to find to enable the i.MX8M's SCU unit. but we can not find any documents or comments about how to use this SCU and where to find reference about it. 

   so , could you please help to solve our puzzle about how to enable A53's SCU or give some suggestions about how to use the A53 multi-core ?

thanks a lot!

社区同仁及NXP专家：

   我们在用MCIMX8M-EVK验证一些测试方面的使用应用。在此应用中，我们需要在u-boot的阶段，将此i.MX8MQ SOC的四个A53 core都运行起来；但是我们遇到了一些使用上的问题；

   当我们把一个task分配给slave core执行的时候，会出现“synchronus abort”同步异常。我们怀疑是我们没有开启SOC里面的SCU单元导致的L1 cache一致性的问题；因此我们尝试找到i.MX8MQ SOC关于如何使用和开启SCU单元的文档和参考，但是看起来，目前这方面的资料都没有找到；

   请问，同仁及NXP的专家，对此问题(A53的SCU或者如何使用A53多核)是否能提供帮助和建议？

   不胜感激

[igorpadykov]

Hi An

typically uboot does not use scu, some exception can be found on:

[U-Boot] [PATCH] ARM: tegra: only enable SCU on Tegra20 

Question may be posted on uboot mail list

U-Boot Info Page 

Best regards
igor
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[anhui527]

hi,igorpadykov

   thanks for your reply.

   our application need to implement some test function in the u-boot stage, at the same time ,our applicaton do need to use multi-core simply and normally which need to enable SCU.

   so , are there any documents or guide about how to enable SCU? and are there any usage example in linux kernel source code which could be seen as a reference for it?

[igorpadykov]

for linux one can look on

https://elinux.org/images/0/00/Clement-smp-bring-up-on-arm-soc.pdf 

Best regards
igor

[anhui527]

hi,igorpadykov

   thanks for your reply.

   Can the method of scu_enable() mentioned in the linked documents be used in armv8 architecture? or this method only could be used in the arch version which is prior to arm v7 ? 

   and could NXP provide some documents about SCU register mapping layout ?

thanks.

[igorpadykov · Accepted solution]

one can post this on kernel linux-smp mail list as this is general linux question

Majordomo Lists at VGER.KERNEL.ORG 

Best regards
igor