On Mon, Feb 24, 2025 at 03:13:52PM +0100, Herve Codina wrote:
> The commit 407d1a51921e ("PCI: Create device tree node for bridge")
> creates of_node for PCI devices. The newly created of_node is attached
> to an existing device. This is done setting directly pdev->dev.of_node
> in the code.
>
> Even if pdev->dev.of_node cannot be previously set, this doesn't handle
> the fwnode field of the struct device. Indeed, this field needs to be
> set if it hasn't already been set.
>
> device_{add,remove}_of_node() have been introduced to handle this case.
I guess another way to say this is:
- If dev->of_node has already been set, it is an error and we want
to do nothing. The error is impossible in this case because
of_pci_make_dev_node() returns early if dev->of_node has been set.
- Otherwise, we want to set dev->of_node (just as we previously
did), and
- if dev->fwnode has not been set, we want to set that too.
So the whole point of this is to set dev->fwnode, which we didn't do
before. But has np->fwnode been set to anything? Maybe it's buried
somewhere inside of_changeset_create_node(), but I didn't see it.
I can't tell if this actually *does* anything. And if it does, all
the above is basically C code translated into English, so it doesn't
tell us *why* this is useful, which is what I try to put in the merge
commit log.
> Use them instead of the direct setting.
>
> Signed-off-by: Herve Codina <herve.codina@xxxxxxxxxxx>
> Reviewed-by: Rob Herring (Arm) <robh@xxxxxxxxxx>
> ---
> drivers/pci/of.c | 11 +++++++++--
> 1 file changed, 9 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/of.c b/drivers/pci/of.c
> index 7a806f5c0d20..fb5e6da1ead0 100644
> --- a/drivers/pci/of.c
> +++ b/drivers/pci/of.c
> @@ -653,8 +653,8 @@ void of_pci_remove_node(struct pci_dev *pdev)
> np = pci_device_to_OF_node(pdev);
> if (!np || !of_node_check_flag(np, OF_DYNAMIC))
> return;
> - pdev->dev.of_node = NULL;
>
> + device_remove_of_node(&pdev->dev);
> of_changeset_revert(np->data);
> of_changeset_destroy(np->data);
> of_node_put(np);
> @@ -711,11 +711,18 @@ void of_pci_make_dev_node(struct pci_dev *pdev)
> goto out_free_node;
>
> np->data = cset;
> - pdev->dev.of_node = np;
> +
> + ret = device_add_of_node(&pdev->dev, np);
> + if (ret)
> + goto out_revert_cset;
> +
> kfree(name);
>
> return;
>
> +out_revert_cset:
> + np->data = NULL;
> + of_changeset_revert(cset);
> out_free_node:
> of_node_put(np);
> out_destroy_cset:
> --
> 2.48.1
>
