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From: dirk.behme@gmail.com (Dirk Behme)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v3] ARM: imx: replicate the diagnostic register of boot cpu into secondary cores
Date: Wed, 01 May 2013 17:32:14 +0200	[thread overview]
Message-ID: <5181357E.3090805@gmail.com> (raw)
In-Reply-To: <20130426134722.GA1943@S2101-09.ap.freescale.net>

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

  reply	other threads:[~2013-05-01 15:32 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-04-26  3:57 [PATCH v3] ARM: imx: replicate the diagnostic register of boot cpu into secondary cores Shawn Guo
2013-04-26 13:21 ` Will Deacon
2013-04-26 13:47   ` Shawn Guo
2013-05-01 15:32     ` Dirk Behme [this message]
2013-05-01 15:38       ` Will Deacon
2013-05-01 16:19         ` Dirk Behme
2013-05-01 16:38           ` Will Deacon
2013-05-02  2:21             ` Shawn Guo
2013-05-02  6:14               ` Dirk Behme

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