[PATCH] ARM: Kconfig: Let ARM_ERRATA_364296 not depend on CONFIG_SMP

[PATCH] ARM: Kconfig: Let ARM_ERRATA_364296 not depend on CONFIG_SMP

[Fabio Estevam]

From: Fabio Estevam <fabio.estevam@freescale.com>

imx_v6_v7_defconfig handles both multi-core and single-core SoCs, and it has 
CONFIG_SMP=y selected by default.

With such config we cannot select ARM_ERRATA_364296, as it depends on !SMP.

Let ARM_ERRATA_364296 be undependent on CONFIG_SMP, so that we can select
this erratum for the ARM1136 SoCs, even if CONFIG_SMP=y is enabled.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
---
 arch/arm/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 0ac9be6..ba412e0 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1316,7 +1316,7 @@ config ARM_ERRATA_754327
 
 config ARM_ERRATA_364296
 	bool "ARM errata: Possible cache data corruption with hit-under-miss enabled"
-	depends on CPU_V6 && !SMP
+	depends on CPU_V6
 	help
 	  This options enables the workaround for the 364296 ARM1136
 	  r0p2 erratum (possible cache data corruption with
-- 
1.8.1.2

[PATCH] ARM: Kconfig: Let ARM_ERRATA_364296 not depend on CONFIG_SMP

[Russell King - ARM Linux]

On Mon, Jul 08, 2013 at 06:38:09PM -0300, Fabio Estevam wrote:
> From: Fabio Estevam <fabio.estevam@freescale.com>
> 
> imx_v6_v7_defconfig handles both multi-core and single-core SoCs, and it has 
> CONFIG_SMP=y selected by default.
> 
> With such config we cannot select ARM_ERRATA_364296, as it depends on !SMP.
> 
> Let ARM_ERRATA_364296 be undependent on CONFIG_SMP, so that we can select
> this erratum for the ARM1136 SoCs, even if CONFIG_SMP=y is enabled.

I'll wait for ARM Ltd folk to comment on this (they're at Linaro Connect
at the moment which has extremely poor 'net connectivity from what I've
been hearing).  We might need to bypass the workaround code in the non-SMP
case.

[PATCH] ARM: Kconfig: Let ARM_ERRATA_364296 not depend on CONFIG_SMP

[Dave Martin]

On Mon, Jul 08, 2013 at 06:38:09PM -0300, Fabio Estevam wrote:
> From: Fabio Estevam <fabio.estevam@freescale.com>
> 
> imx_v6_v7_defconfig handles both multi-core and single-core SoCs, and it has 
> CONFIG_SMP=y selected by default.
> 
> With such config we cannot select ARM_ERRATA_364296, as it depends on !SMP.
> 
> Let ARM_ERRATA_364296 be undependent on CONFIG_SMP, so that we can select
> this erratum for the ARM1136 SoCs, even if CONFIG_SMP=y is enabled.
> 
> Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>

This looks sensible.  The enabled code checks for the specific
affected CPU ID in the CP15 Main ID Register, so it shouldn't get
activated on any other kind of CPU even if the option is enabled.

1136 can't be deployed as SMP, so the patch shouldn't break any existing
configuration.

Strictly speaking, && !SMP may be incorrect, since it is valid (if not
very useful) to build a v6 kernel with SMP and SMP_ON_UP, and run it on
1136 hardware, even if the kernel is non-multiplatform.

Reviewed-by: Dave Martin <Dave.Martin@arm.com>

> ---
>  arch/arm/Kconfig | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 0ac9be6..ba412e0 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -1316,7 +1316,7 @@ config ARM_ERRATA_754327
>  
>  config ARM_ERRATA_364296
>  	bool "ARM errata: Possible cache data corruption with hit-under-miss enabled"
> -	depends on CPU_V6 && !SMP
> +	depends on CPU_V6
>  	help
>  	  This options enables the workaround for the 364296 ARM1136
>  	  r0p2 erratum (possible cache data corruption with
> -- 
> 1.8.1.2
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel at lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH] ARM: Kconfig: Let ARM_ERRATA_364296 not depend on CONFIG_SMP

[Will Deacon]

On Mon, Jul 08, 2013 at 10:53:20PM +0100, Russell King - ARM Linux wrote:
> On Mon, Jul 08, 2013 at 06:38:09PM -0300, Fabio Estevam wrote:
> > From: Fabio Estevam <fabio.estevam@freescale.com>
> > 
> > imx_v6_v7_defconfig handles both multi-core and single-core SoCs, and it has 
> > CONFIG_SMP=y selected by default.
> > 
> > With such config we cannot select ARM_ERRATA_364296, as it depends on !SMP.
> > 
> > Let ARM_ERRATA_364296 be undependent on CONFIG_SMP, so that we can select
> > this erratum for the ARM1136 SoCs, even if CONFIG_SMP=y is enabled.
> 
> I'll wait for ARM Ltd folk to comment on this (they're at Linaro Connect
> at the moment which has extremely poor 'net connectivity from what I've
> been hearing).  We might need to bypass the workaround code in the non-SMP
> case.

The workaround (in proc-v6.S) checks the midr specifically for 1136 r0p2, so
it should be fine to remove the CONFIG_SMP dependency given that the 1136 is
UP only.

Will

[PATCH] ARM: Kconfig: Let ARM_ERRATA_364296 not depend on CONFIG_SMP

[Catalin Marinas]

On Mon, Jul 08, 2013 at 10:38:09PM +0100, Fabio Estevam wrote:
> From: Fabio Estevam <fabio.estevam@freescale.com>
> 
> imx_v6_v7_defconfig handles both multi-core and single-core SoCs, and it has 
> CONFIG_SMP=y selected by default.
> 
> With such config we cannot select ARM_ERRATA_364296, as it depends on !SMP.
> 
> Let ARM_ERRATA_364296 be undependent on CONFIG_SMP, so that we can select
> this erratum for the ARM1136 SoCs, even if CONFIG_SMP=y is enabled.
> 
> Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>

I've just seen the patch (long email backlog).

Acked-by: Catalin Marinas <catalin.marinas@arm.com>