[PATCH v3] ARM: imx: replicate the diagnostic register of boot cpu into secondary cores

[Dirk Behme]

Am 26.04.2013 15:47, schrieb Shawn Guo:
> On Fri, Apr 26, 2013 at 02:21:30PM +0100, Will Deacon wrote:
>>> diff --git a/arch/arm/mach-imx/headsmp.S b/arch/arm/mach-imx/headsmp.S
>>> index a58c8b0..cd87970 100644
>>> --- a/arch/arm/mach-imx/headsmp.S
>>> +++ b/arch/arm/mach-imx/headsmp.S
>>> @@ -18,8 +18,20 @@
>>>   	.section ".text.head", "ax"
>>>
>>>   #ifdef CONFIG_SMP
>>> +diag_reg_offset:
>>> +	.word	g_diag_reg - .
>>> +
>>> +	.macro	set_diag_reg
>>> +	adr	r0, diag_reg_offset
>>> +	ldr	r1, [r0]
>>> +	add	r1, r1, r0		@ r1 = physical &g_diag_reg
>>> +	ldr	r0, [r1]
>>> +	mcr	p15, 0, r0, c15, c0, 1	@ write diagnostic register
>>> +	.endm
>>
>> Why not re-read the register directly, rather than mrc on the current core?
>
> I do not understand the comment.  What do you mean by "re-read"?  Read
> the register on secondary cores will only return us 0, as bootloader
> only sets up the register on cpu0.  The macro set_diag_reg only runs on
> secondary cores to copy cpu0's diagnostic bits.  I think it's safe on
> SMP.

Any news on this?

Thanks

Dirk