From mboxrd@z Thu Jan  1 00:00:00 1970
From: dirk.behme@gmail.com (Dirk Behme)
Date: Wed, 01 May 2013 17:32:14 +0200
Subject: [PATCH v3] ARM: imx: replicate the diagnostic register of boot
 cpu into secondary cores
In-Reply-To: <20130426134722.GA1943@S2101-09.ap.freescale.net>
References: <1366948645-12060-1-git-send-email-shawn.guo@linaro.org>
 <20130426132130.GE30858@mudshark.cambridge.arm.com>
 <20130426134722.GA1943@S2101-09.ap.freescale.net>
Message-ID: <5181357E.3090805@gmail.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

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