[3.16.y-ckt stable] Patch "ARM: mvebu: make the coherency_ll.S functions work with no coherency fabric" has been added to staging queue

[Luis Henriques]

On Wed, Jan 07, 2015 at 10:29:02AM +0000, Luis Henriques wrote:
> This is a note to let you know that I have just added a patch titled
> 
>     ARM: mvebu: make the coherency_ll.S functions work with no coherency fabric
> 
> to the linux-3.16.y-queue branch of the 3.16.y-ckt extended stable tree 
> which can be found at:
> 
>  http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.16.y-queue
> 
> This patch is scheduled to be released in version 3.16.7-ckt4.
> 
> If you, or anyone else, feels it should not be added to this tree, please 
> reply to this email.
>

Actually, this patch is breaking the builds of 3.16 kernel using
configs mvebu_v7_defconfig and multi_v7_defconfig:

arch/arm/mach-mvebu/coherency_ll.S: Assembler messages:
arch/arm/mach-mvebu/coherency_ll.S:98: Error: bad instruction `reteq r0'
arch/arm/mach-mvebu/coherency_ll.S:123: Error: bad instruction `reteq r0'
arch/arm/mach-mvebu/coherency_ll.S:150: Error: bad instruction `reteq r0'

Mainline builds fine, so I assume I'm missing some other patch, but I
couldn't find out which one.  Any ideas, or shall I just drop this
from the queue?

Cheers,
--
Luís


> For more information about the 3.16.y-ckt tree, see
> https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
> 
> Thanks.
> -Luis
> 
> ------
> 
> From 61536b3b3703c070a753fde94c3c41b1239b2388 Mon Sep 17 00:00:00 2001
> From: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
> Date: Thu, 13 Nov 2014 10:38:56 +0100
> Subject: ARM: mvebu: make the coherency_ll.S functions work with no coherency
>  fabric
> 
> commit 30cdef97107370a7f63ab5d80fd2de30540750c8 upstream.
> 
> The ll_add_cpu_to_smp_group(), ll_enable_coherency() and
> ll_disable_coherency() are used on Armada XP to control the coherency
> fabric. However, they make the assumption that the coherency fabric is
> always available, which is currently a correct assumption but will no
> longer be true with a followup commit that disables the usage of the
> coherency fabric when the conditions are not met to use it.
> 
> Therefore, this commit modifies those functions so that they check the
> return value of ll_get_coherency_base(), and if the return value is 0,
> they simply return without configuring anything in the coherency
> fabric.
> 
> The ll_get_coherency_base() function is also modified to properly
> return 0 when the function is called with the MMU disabled. In this
> case, it normally returns the physical address of the coherency
> fabric, but we now check if the virtual address is 0, and if that's
> case, return a physical address of 0 to indicate that the coherency
> fabric is not enabled.
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
> Acked-by: Gregory CLEMENT <gregory.clement at free-electrons.com>
> Link: https://lkml.kernel.org/r/1415871540-20302-2-git-send-email-thomas.petazzoni@free-electrons.com
> Signed-off-by: Jason Cooper <jason at lakedaemon.net>
> Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
> ---
>  arch/arm/mach-mvebu/coherency_ll.S | 21 +++++++++++++++++++--
>  1 file changed, 19 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm/mach-mvebu/coherency_ll.S b/arch/arm/mach-mvebu/coherency_ll.S
> index 510c29e079ca..13dfa92c84b6 100644
> --- a/arch/arm/mach-mvebu/coherency_ll.S
> +++ b/arch/arm/mach-mvebu/coherency_ll.S
> @@ -24,7 +24,10 @@
>  #include <asm/cp15.h>
> 
>  	.text
> -/* Returns the coherency base address in r1 (r0 is untouched) */
> +/*
> + * Returns the coherency base address in r1 (r0 is untouched), or 0 if
> + * the coherency fabric is not enabled.
> + */
>  ENTRY(ll_get_coherency_base)
>  	mrc	p15, 0, r1, c1, c0, 0
>  	tst	r1, #CR_M @ Check MMU bit enabled
> @@ -32,8 +35,13 @@ ENTRY(ll_get_coherency_base)
> 
>  	/*
>  	 * MMU is disabled, use the physical address of the coherency
> -	 * base address.
> +	 * base address. However, if the coherency fabric isn't mapped
> +	 * (i.e its virtual address is zero), it means coherency is
> +	 * not enabled, so we return 0.
>  	 */
> +	ldr	r1, =coherency_base
> +	cmp	r1, #0
> +	beq	2f
>  	adr	r1, 3f
>  	ldr	r3, [r1]
>  	ldr	r1, [r1, r3]
> @@ -85,6 +93,9 @@ ENTRY(ll_add_cpu_to_smp_group)
>  	 */
>  	mov 	r0, lr
>  	bl	ll_get_coherency_base
> +	/* Bail out if the coherency is not enabled */
> +	cmp	r1, #0
> +	reteq	r0
>  	bl	ll_get_coherency_cpumask
>  	mov 	lr, r0
>  	add	r0, r1, #ARMADA_XP_CFB_CFG_REG_OFFSET
> @@ -107,6 +118,9 @@ ENTRY(ll_enable_coherency)
>  	 */
>  	mov r0, lr
>  	bl	ll_get_coherency_base
> +	/* Bail out if the coherency is not enabled */
> +	cmp	r1, #0
> +	reteq	r0
>  	bl	ll_get_coherency_cpumask
>  	mov lr, r0
>  	add	r0, r1, #ARMADA_XP_CFB_CTL_REG_OFFSET
> @@ -131,6 +145,9 @@ ENTRY(ll_disable_coherency)
>  	 */
>  	mov 	r0, lr
>  	bl	ll_get_coherency_base
> +	/* Bail out if the coherency is not enabled */
> +	cmp	r1, #0
> +	reteq	r0
>  	bl	ll_get_coherency_cpumask
>  	mov 	lr, r0
>  	add	r0, r1, #ARMADA_XP_CFB_CTL_REG_OFFSET
> --
> 2.1.4
>