[U-Boot] [PATCH v2 1/2] configs: mx6_common: Restrict CONFIG_ARM_ERRATA_742230 for multi-core

[Stefano Babic]

Hi Shawn,

On 09/01/2014 07:28, Shawn Guo wrote:
> On Thu, Jan 09, 2014 at 03:50:06AM +0000, Hui.Liu at freescale.com wrote:
>> The commit log really get me confused, why we need enable one ERRATA which should not be applied?
> 
> It's been enabled as a workaround for the reboot issue we were seeing
> before.  But I get reminded that the workaround may not be needed
> anymore, because of the recent kernel commit 87a84b69 (ARM: imx: replace
> imx6q_restart() with mxc_restart()).  The real change is that we do not
> call of_iomap() in restart hook now.
> 
> Fabio,
> 
> Can you give it a test to see if reboot works fine with v3.13-rc kernel
> with dropping the ERRATA from u-boot?  If reboot works and nothing else
> breaks, we may want to just remove the ERRATA selection from u-boot.
> 

+1

If the workaround must be set for dual/quad, it is not clear to me if
there are some disadvantages to let it enabled for solo.


>> This will make customer confused at all. We need find the real root-cause for it other than hack it
>> Otherwise, you will get more and more problems sooner or later...
> 
> If you go through the thread [1], you will see that the root-cause had
> pretty much been identified, - issuing dmb instructions in a tight loop
> causes the problem.  But people did not reach a conclusion how it should
> be fixed.

Exactly, and more frightening IMHO is what can happen is user space if
gcc uses dmb.

Regards,
Stefano

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