Messages in this thread | | | From | Andy Shevchenko <> | Date | Tue, 15 Dec 2020 19:49:14 +0200 | Subject | Re: [net-next PATCH v2 10/14] device property: Introduce fwnode_get_id() |
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On Tue, Dec 15, 2020 at 7:00 PM Laurent Pinchart <laurent.pinchart@ideasonboard.com> wrote: > On Tue, Dec 15, 2020 at 10:13:11PM +0530, Calvin Johnson wrote: > > Using fwnode_get_id(), get the reg property value for DT node > > and get the _ADR object value for ACPI node.
...
> > +/** > > + * fwnode_get_id - Get the id of a fwnode. > > + * @fwnode: firmware node > > + * @id: id of the fwnode > > Is the concept of fwnode ID documented clearly somewhere ? I think this > function should otherwise have more documentation, at least to explain > what the ID is.
I'm afraid that OF has no clear concept of this either. It's usually used as a unique ID for the children of some device (like MFD) and can represent a lot of things. But I agree it should be documented.
Rob, any ideas about this?
> > + * Returns 0 on success or a negative errno. > > + */ > > +int fwnode_get_id(struct fwnode_handle *fwnode, u32 *id) > > +{ > > + unsigned long long adr; > > + acpi_status status; > > + > > + if (is_of_node(fwnode)) { > > + return of_property_read_u32(to_of_node(fwnode), "reg", id); > > + } else if (is_acpi_node(fwnode)) { > > + status = acpi_evaluate_integer(ACPI_HANDLE_FWNODE(fwnode), > > + METHOD_NAME__ADR, NULL, &adr); > > + if (ACPI_FAILURE(status)) > > + return -ENODATA; > > Would it make sense to standardize error codes ? of_property_read_u32() > can return -EINVAL, -ENODATA or -EOVERFLOW. I don't think the caller of > this function would be very interested to tell those three cases apart. > Maybe we should return -EINVAL in all error cases ? Or maybe different > error codes to mean "the backend doesn't support the concept of IDs", > and "the device doesn't have an ID" ?
We may actually get mapping to all three if first we check for the method/name existence followed by value check. But I don't think we need to bloat this simple one.
> > + *id = (u32)adr; > > + return 0; > > + } > > + return -EINVAL; > > +}
-- With Best Regards, Andy Shevchenko
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