On 2020-08-26 07:02, Matthias Schiffer wrote:
> Allow disabling CPU nodes using status = "disabled".
>
> This allows a bootloader to change the number of available CPUs (for
> example when a common DTS is used for SoC variants with different numbers
> of cores) without deleting the nodes altogether (which may require
> additional fixups where the CPU nodes are referenced, e.g. a cooling
> map).
>
> Signed-off-by: Matthias Schiffer <matthias.schiffer@xxxxxxxxxxxxxxx>
> ---
> drivers/of/base.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index ea44fea99813..d547e9deced1 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -796,6 +796,8 @@ struct device_node *of_get_next_cpu_node(struct device_node *prev)
> of_node_put(node);
> }
> for (; next; next = next->sibling) {
> + if (!__of_device_is_available(next))
> + continue;
> if (!(of_node_name_eq(next, "cpu") ||
> __of_node_is_type(next, "cpu")))
> continue;
>
The original implementation of of_get_next_cpu_node() had
that check, but status disabled for cpu nodes has different
semantics than other nodes, and the check broke some systems.
The check was removed by c961cb3be906 "of: Fix cpu node
iterator to not ignore disabled cpu nodes".
It would be useful to document that difference in the
header comment of of_get_next_cpu_node().
-Frank
