From mboxrd@z Thu Jan  1 00:00:00 1970
From: dinguyen@opensource.altera.com (Dinh Nguyen)
Date: Wed, 8 Jul 2015 16:55:52 -0500
Subject: [PATCH] ARM: socfpga: put back v7_invalidate_l1 in
 socfpga_secondary_startup
In-Reply-To: <20150708210734.GN7557@n2100.arm.linux.org.uk>
References: <1436370711-18524-1-git-send-email-dinguyen@opensource.altera.com>
 <20150708165115.GM7557@n2100.arm.linux.org.uk>
 <559D765C.30102@opensource.altera.com>
 <20150708210734.GN7557@n2100.arm.linux.org.uk>
Message-ID: <559D9C68.6030907@opensource.altera.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 07/08/2015 04:07 PM, Russell King - ARM Linux wrote:
> On Wed, Jul 08, 2015 at 02:13:32PM -0500, Dinh Nguyen wrote:
>> The value of CPACR is 0x00F00000. So cp11 and cp10 are privileged and
>> user mode access.
> 
> Hmm.
> 
> I think what you've found is a(nother) latent bug in the CPU bring up
> code.
> 
> For SMP CPUs, the sequence we're following during early initialisation is:
> 
> 1. Enable SMP coherency.
> 2. Invalidate the caches.
> 
> If the cache contains rubbish, enabling SMP coherency before invalidating
> the cache is plainly an absurd thing to do.
> 
> Can you try the patch below - not tested in any way, so you may need to
> tweak it, but it should allow us to prove that point.
> 
> diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S
> index 0716bbe19872..db5137fc297d 100644
> --- a/arch/arm/mm/proc-v7.S
> +++ b/arch/arm/mm/proc-v7.S
> @@ -275,6 +275,10 @@ __v7_b15mp_setup:
>  __v7_ca17mp_setup:
>  	mov	r10, #0
>  1:
> +	adr	r12, __v7_setup_stack		@ the local stack
> +	stmia	r12, {r0-r5, r7, r9-r11, lr}
> +	bl      v7_invalidate_l1
> +	ldmia	r12, {r0-r5, r7, r9-r11, lr}
>  #ifdef CONFIG_SMP
>  	ALT_SMP(mrc	p15, 0, r0, c1, c0, 1)
>  	ALT_UP(mov	r0, #(1 << 6))		@ fake it for UP
> @@ -283,7 +287,7 @@ __v7_ca17mp_setup:
>  	orreq	r0, r0, r10			@ Enable CPU-specific SMP bits
>  	mcreq	p15, 0, r0, c1, c0, 1
>  #endif
> -	b	__v7_setup
> +	b	__v7_setup_cont
>  
>  /*
>   * Errata:
> @@ -417,6 +421,7 @@ __v7_setup:
>  	bl      v7_invalidate_l1
>  	ldmia	r12, {r0-r5, r7, r9, r11, lr}
>  
> +__v7_setup_cont:
>  	and	r0, r9, #0xff000000		@ ARM?
>  	teq	r0, #0x41000000
>  	bne	__errata_finish
> @@ -480,7 +485,7 @@ ENDPROC(__v7_setup)
>  
>  	.align	2
>  __v7_setup_stack:
> -	.space	4 * 11				@ 11 registers
> +	.space	4 * 12				@ 12 registers
>  
>  	__INITDATA
>  
> 


This patch seems to have fixed the issue. The SoCFPGA platform is now
booting/rebooting reliably. Also, the patch was applicable as-is.

Also, I went back and studied up on the CPACR register. I misquoted the
value in my previous response, I was looking at CPACR on CPU0. For CPU1,
when the error happens, the value of CPACR is 0x0, so CP10 and CP11 were
set to "Access denied".

Dinh