arm64: Clarify when cpu_enable() is called

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>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
[will: minor tweak to emphasis in the comment]
Signed-off-by: Will Deacon <will@kernel.org>

diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index cf65a47..9cde5d2 100644 (file)
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -289,9 +289,16 @@ 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 whether the
+        * capability is 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 {