Re: [PATCH v4 1/6] driver core: Introduce device_{add,remove}_of_node()

Greg Kroah-Hartman
2024-12-05T07:00:47Z

On Wed, Dec 04, 2024 at 03:38:25PM -0600, Bjorn Helgaas wrote:
> [cc->to Greg, Rafael]
>
> On Mon, Dec 02, 2024 at 02:15:13PM +0100, Herve Codina wrote:
> > An of_node can be set to a device using device_set_node().
> > This function cannot prevent any of_node and/or fwnode overwrites.
> >
> > When adding an of_node on an already present device, the following
> > operations need to be done:
> > - Attach the of_node if no of_node were already attached
> > - Attach the of_node as a fwnode if no fwnode were already attached
> >
> > This is the purpose of device_add_of_node().
> > device_remove_of_node() reverts the operations done by
> > device_add_of_node().
> >
> > Signed-off-by: Herve Codina <herve.codina@bootlin.com>
> > ---
> > drivers/base/core.c | 52 ++++++++++++++++++++++++++++++++++++++++++
> > include/linux/device.h | 2 ++
>
> I suppose this series would go via the PCI tree since the bulk of the
> changes are there. If so, I would look for an ack from the driver
> core folks (Greg, Rafael).
>
> > 2 files changed, 54 insertions(+)
> >
> > diff --git a/drivers/base/core.c b/drivers/base/core.c
> > index 8b056306f04e..3953c5ab7316 100644
> > --- a/drivers/base/core.c
> > +++ b/drivers/base/core.c
> > @@ -5216,6 +5216,58 @@ void set_secondary_fwnode(struct device *dev, struct fwnode_handle *fwnode)
> > }
> > EXPORT_SYMBOL_GPL(set_secondary_fwnode);
> >
> > +/**
> > + * device_remove_of_node - Remove an of_node from a device
> > + * @dev: device whose device-tree node is being removed
> > + */
> > +void device_remove_of_node(struct device *dev)
> > +{
> > + dev = get_device(dev);
> > + if (!dev)
> > + return;
> > +
> > + if (!dev->of_node)
> > + goto end;
> > +
> > + if (dev->fwnode == of_fwnode_handle(dev->of_node))
> > + dev->fwnode = NULL;
> > +
> > + of_node_put(dev->of_node);
> > + dev->of_node = NULL;
> > +
> > +end:
> > + put_device(dev);
> > +}
> > +EXPORT_SYMBOL_GPL(device_remove_of_node);
> > +
> > +/**
> > + * device_add_of_node - Add an of_node to an existing device
> > + * @dev: device whose device-tree node is being added
> > + * @of_node: of_node to add
> > + */
> > +void device_add_of_node(struct device *dev, struct device_node *of_node)
> > +{
> > + if (!of_node)
> > + return;
> > +
> > + dev = get_device(dev);
> > + if (!dev)
> > + return;
> > +
> > + if (WARN(dev->of_node, "%s: Cannot replace node %pOF with %pOF\n",
> > + dev_name(dev), dev->of_node, of_node))
> > + goto end;

Please do not reboot machines that have panic-on-warn for something that
you can properly handle and recover from (like this.) Just print out a
message and continue on, or better yet, return an error if this didn't
work properly.

thanks,

greg k-h