[PATCH v2] arm64: Clarify when cpu_enable() is called

[PATCH v2] arm64: Clarify when cpu_enable() is called

[Mark Brown]

Strengthen the wording in the documentation for cpu_enable() to make it
more obvious to readers not already familiar with the code when the core
will call this callback and that this is intentional.

Signed-off-by: Mark Brown <broonie@kernel.org>
---

v2: Much more verbose wording from Suzuki.

 arch/arm64/include/asm/cpufeature.h | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index cf65a47ee6b4..2447d4afbf54 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -289,9 +289,17 @@ struct arm64_cpu_capabilities {
 	u16 type;
 	bool (*matches)(const struct arm64_cpu_capabilities *caps, int scope);
 	/*
-	 * Take the appropriate actions to enable this capability for this CPU.
-	 * For each successfully booted CPU, this method is called for each
-	 * globally detected capability.
+	 * Take the appropriate actions to configure this capability
+	 * for this CPU.  If the capability is detected by the kernel
+	 * this will be called on all the CPUs in the system,
+	 * including the hotplugged CPUs, regardless of if the
+	 * capability was *available* on that specific CPU. This is
+	 * useful for some capabilities (e.g, working around CPU
+	 * errata), where all the CPUs must take some action (e.g,
+	 * changing system control/configuration).  Thus, if an action
+	 * is required only if the CPU has the capability then the
+	 * routine must check it before taking any action.
+
 	 */
 	void (*cpu_enable)(const struct arm64_cpu_capabilities *cap);
 	union {
-- 
2.20.1


_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH v2] arm64: Clarify when cpu_enable() is called

[Suzuki K Poulose]

On 08/08/2019 14:53, Mark Brown wrote:
> Strengthen the wording in the documentation for cpu_enable() to make it
> more obvious to readers not already familiar with the code when the core
> will call this callback and that this is intentional.
> 

Looks good to me, except for some minor space related issues below.

> Signed-off-by: Mark Brown <broonie@kernel.org>
> ---
> 
> v2: Much more verbose wording from Suzuki.
> 
>   arch/arm64/include/asm/cpufeature.h | 14 +++++++++++---
>   1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
> index cf65a47ee6b4..2447d4afbf54 100644
> --- a/arch/arm64/include/asm/cpufeature.h
> +++ b/arch/arm64/include/asm/cpufeature.h
> @@ -289,9 +289,17 @@ struct arm64_cpu_capabilities {
>   	u16 type;
>   	bool (*matches)(const struct arm64_cpu_capabilities *caps, int scope);
>   	/*
> -	 * Take the appropriate actions to enable this capability for this CPU.
> -	 * For each successfully booted CPU, this method is called for each
> -	 * globally detected capability.
> +	 * Take the appropriate actions to configure this capability
> +	 * for this CPU.  If the capability is detected by the kernel

minor nit: double space ^^

> +	 * this will be called on all the CPUs in the system,
> +	 * including the hotplugged CPUs, regardless of if the
> +	 * capability was *available* on that specific CPU. This is
> +	 * useful for some capabilities (e.g, working around CPU
> +	 * errata), where all the CPUs must take some action (e.g,
> +	 * changing system control/configuration).  Thus, if an action

and here before "Thus".

> +	 * is required only if the CPU has the capability then the
> +	 * routine must check it before taking any action.
> +

spurious new line ?

>   	 */
>   	void (*cpu_enable)(const struct arm64_cpu_capabilities *cap);
>   	union {
> 

With the above addressed,

Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel