Quoting Saravana Kannan (2021-03-30 11:50:55) > remote-endpoint property seems to always come in pairs where two devices > point to each other. So, we can't really tell from DT if there is a > functional probe order dependency between these two devices. > > However, there can be other dependencies between two devices that point > to each other with remote-endpoint. This non-remote-endpoint dependency > combined with one of the remote-endpoint dependency can lead to a cyclic > dependency[1]. > > To avoid this cyclic dependency from incorrectly blocking probes, > fw_devlink needs to be made aware of remote-endpoint dependencies even > though remote-endpoint dependencies by themselves won't affect probe > ordering (because fw_devlink will see the cyclic dependency between > remote-endpoint devices and ignore the dependencies that cause the > cycle). > > Also, if a device ever needs to know if a non-probe-blocking > remote-endpoint has finished probing, it can now use the sync_state() to > figure it out. > > [1] - https://lore.kernel.org/lkml/CAGETcx9Snf23wrXqjDhJiTok9M3GcoVYDSyNYSMj9QnSRrA=cA@xxxxxxxxxxxxxx/#t > Fixes: ea718c699055 ("Revert "Revert "driver core: Set fw_devlink=on by default""") > Reported-by: Stephen Boyd <swboyd@xxxxxxxxxxxx> > Signed-off-by: Saravana Kannan <saravanak@xxxxxxxxxx> > --- Tested-by: Stephen Boyd <swboyd@xxxxxxxxxxxx> > diff --git a/drivers/of/property.c b/drivers/of/property.c > index 5036a362f52e..2bb3158c9e43 100644 > --- a/drivers/of/property.c > +++ b/drivers/of/property.c > @@ -1225,6 +1230,8 @@ static struct device_node *parse_##fname(struct device_node *np, \ > * @parse_prop.prop_name: Name of property holding a phandle value > * @parse_prop.index: For properties holding a list of phandles, this is the > * index into the list > + * @optional: The property can be an optional dependency. This bit conflicted for me on linux-next today so I dropped it in favor of 3915fed92365 ("of: property: Provide missing member description and remove excess param"). > + * @node_not_dev: The consumer node containing the property is never a device. > * > * Returns: > * parse_prop() return values are
