diff options
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/fwnode.h | 21 |
1 files changed, 19 insertions, 2 deletions
diff --git a/include/linux/fwnode.h b/include/linux/fwnode.h index 6ae05b9ce359..97223e2410bd 100644 --- a/include/linux/fwnode.h +++ b/include/linux/fwnode.h @@ -71,8 +71,25 @@ struct fwnode_reference_args { * links to all the suppliers of the device that are available at * the time this function is called. The function must NOT stop * at the first failed device link if other unlinked supplier - * devices are present in the system. If some suppliers are not - * yet available, this function will be called again when other + * devices are present in the system. This is necessary for the + * driver/bus sync_state() callbacks to work correctly. + * + * For example, say Device-C depends on suppliers Device-S1 and + * Device-S2 and the dependency is listed in that order in the + * firmware. Say, S1 gets populated from the firmware after + * late_initcall_sync(). Say S2 is populated and probed way + * before that in device_initcall(). When C is populated, if this + * add_links() function doesn't continue past a "failed linking to + * S1" and continue linking C to S2, then S2 will get a + * sync_state() callback before C is probed. This is because from + * the perspective of S2, C was never a consumer when its + * sync_state() evaluation is done. To avoid this, the add_links() + * function has to go through all available suppliers of the + * device (that corresponds to this fwnode) and link to them + * before returning. + * + * If some suppliers are not yet available (indicated by an error + * return value), this function will be called again when other * devices are added to allow creating device links to any newly * available suppliers. * |