From: gregory.clement@free-electrons•com (Gregory CLEMENT)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCHv2 1/3] ARM: mvebu: make the coherency_ll.S functions work with no coherency fabric
Date: Fri, 31 Oct 2014 14:39:39 +0100 [thread overview]
Message-ID: <5453911B.5090306@free-electrons.com> (raw)
In-Reply-To: <1414423955-5933-2-git-send-email-thomas.petazzoni@free-electrons.com>
Hi Thomas,
On 27/10/2014 16:32, Thomas Petazzoni wrote:
> 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@free-electrons•com>
> Cc: <stable@vger•kernel.org> # v3.8+
> ---
> 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 f5d881b..0ed07c3 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
> + moveq pc, r0
Since the commit "6ebbf2ce437b33022d30badd49dc94d33ecfa498:
ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+", you should
use "reteq r0" instead of "moveq pc, 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
> + moveq pc, r0
Same here
> 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
> + moveq pc, r0
and same here
> bl ll_get_coherency_cpumask
> mov lr, r0
> add r0, r1, #ARMADA_XP_CFB_CTL_REG_OFFSET
>
Besides this small changes:
Acked-by: Gregory CLEMENT <gregory.clement@free-electrons•com>
Thanks,
Gregory
--
Gregory Clement, Free Electrons
Kernel, drivers, real-time and embedded Linux
development, consulting, training and support.
http://free-electrons.com
next prev parent reply other threads:[~2014-10-31 13:39 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-27 15:32 [PATCHv2 0/3] ARM: mvebu: disable I/O coherency on !SMP Thomas Petazzoni
2014-10-27 15:32 ` [PATCHv2 1/3] ARM: mvebu: make the coherency_ll.S functions work with no coherency fabric Thomas Petazzoni
2014-10-31 13:39 ` Gregory CLEMENT [this message]
2014-10-27 15:32 ` [PATCHv2 2/3] ARM: mvebu: disable I/O coherency on non-SMP situations on Armada 370/XP Thomas Petazzoni
2014-10-31 13:46 ` Gregory CLEMENT
2014-11-07 2:53 ` Jason Cooper
2014-10-27 15:32 ` [PATCHv2 3/3] ARM: mvebu: add missing of_node_put() call in coherency.c Thomas Petazzoni
2014-10-31 13:49 ` Gregory CLEMENT
2014-11-07 2:57 ` Jason Cooper
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