On 11/8/21 3:48 AM, Matthias Schiffer wrote: > Allow fully disabling CPU nodes using status = "fail". Having no status > property at all is still interpreted as "okay" as usual. > > 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 could require > additional fixups to avoid dangling phandle references. > > References: > - https://www.lkml.org/lkml/2020/8/26/1237 > - https://www.spinics.net/lists/devicetree-spec/msg01007.html > - https://github.com/devicetree-org/dt-schema/pull/61 > > Signed-off-by: Matthias Schiffer <matthias.schiffer@xxxxxxxxxxxxxxx> > --- > drivers/of/base.c | 29 +++++++++++++++++++++++++++++ > 1 file changed, 29 insertions(+) > > diff --git a/drivers/of/base.c b/drivers/of/base.c > index 61de453b885c..4e9973627c8d 100644 > --- a/drivers/of/base.c > +++ b/drivers/of/base.c > @@ -650,6 +650,32 @@ bool of_device_is_available(const struct device_node *device) > } > EXPORT_SYMBOL(of_device_is_available); > > +/** > + * __of_device_is_disabled - check if a device has status "disabled" > + * > + * @device: Node to check status for, with locks already held > + * > + * Return: True if the status property is set to "disabled", > + * false otherwise > + * > + * Most callers should use __of_device_is_available() instead, this function > + * only exists due to the special interpretation of the "disabled" status for > + * CPU nodes. > + */ > +static bool __of_device_is_disabled(const struct device_node *device) > +{ > + const char *status; > + > + if (!device) > + return false; > + > + status = __of_get_property(device, "status", NULL); > + if (status == NULL) > + return false; > + > + return !strcmp(status, "disabled"); > +} > + > /** > * of_device_is_big_endian - check if a device has BE registers > * > @@ -817,6 +843,9 @@ 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) && > + !__of_device_is_disabled(next)) Shouldn't that just be a check to continue if the device is disabled? If adding a check for available, then all of the callers of for_each_of_cpu_node() need to be checked. There is at least one that is suspicious - arch/arm/mach-imx/platsmp.c has a comment: * Initialise the CPU possible map early - this describes the CPUs * which may be present or become present in the system. -Frank > + continue; > if (!(of_node_name_eq(next, "cpu") || > __of_node_is_type(next, "cpu"))) > continue; >
