On 11/22/21 6:45 AM, Matthias Schiffer wrote: > Allow fully disabling CPU nodes using status = "fail". > > 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. > > Unknown status values (everything that is not "okay"/"ok", "disabled" or > "fail"/"fail-...") will continue to be interpreted like "disabled", > meaning that the CPU can be enabled during boot. > Thank you for including all the references! I find them helpful. > References: > - https://www.lkml.org/lkml/2020/8/26/1237 That reference should be: https://lore.kernel.org/all/CAL_Jsq+1LsTBdVaODVfmB0eme2jMpNL4VgKk-OM7rQWyyF0Jbw@xxxxxxxxxxxxxx/ Rob might be willing to fix that himself without a new patch version. > - https://www.spinics.net/lists/devicetree-spec/msg01007.html The following reference is the pull request for the devicetree specification change that is provided in the previous reference. I wouldn't include this in the commit, but maybe Rob will. > - https://github.com/devicetree-org/dt-schema/pull/61 > > Signed-off-by: Matthias Schiffer <matthias.schiffer@xxxxxxxxxxxxxxx> > --- > > v2: Treat unknown status values like "disabled", not like "fail" > > > drivers/of/base.c | 27 +++++++++++++++++++++++++++ > 1 file changed, 27 insertions(+) > > diff --git a/drivers/of/base.c b/drivers/of/base.c > index 61de453b885c..5b907600f5b0 100644 > --- a/drivers/of/base.c > +++ b/drivers/of/base.c > @@ -650,6 +650,28 @@ bool of_device_is_available(const struct device_node *device) > } > EXPORT_SYMBOL(of_device_is_available); > > +/** > + * __of_device_is_fail - check if a device has status "fail" or "fail-..." > + * > + * @device: Node to check status for, with locks already held > + * > + * Return: True if the status property is set to "fail" or "fail-..." (for any > + * error code suffix), false otherwise > + */ > +static bool __of_device_is_fail(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, "fail") || !strncmp(status, "fail-", 5); > +} > + > /** > * of_device_is_big_endian - check if a device has BE registers > * > @@ -796,6 +818,9 @@ EXPORT_SYMBOL(of_get_next_available_child); > * of_get_next_cpu_node - Iterate on cpu nodes > * @prev: previous child of the /cpus node, or NULL to get first > * > + * Unusable CPUs (those with the status property set to "fail" or "fail-...") > + * will be skipped. > + * > * Return: A cpu node pointer with refcount incremented, use of_node_put() > * on it when done. Returns NULL when prev is the last child. Decrements > * the refcount of prev. > @@ -817,6 +842,8 @@ struct device_node *of_get_next_cpu_node(struct device_node *prev) > of_node_put(node); > } This comment is being really picky. I would put the check for status value of fail after the check of node name. If Rob is willing to accept this version I am ok with it. > for (; next; next = next->sibling) { > + if (__of_device_is_fail(next)) > + continue; > if (!(of_node_name_eq(next, "cpu") || > __of_node_is_type(next, "cpu"))) > continue; > Reviewed-by: Frank Rowand <frank.rowand@xxxxxxxx>
