Re: [PATCH 15/17] pci: of_property: Add the interrupt-controller property in PCI device nodes

From: Bjorn Helgaas
Date: Wed May 01 2024 - 13:38:40 EST


In subject: s/pci:/PCI:/ to match history. s/Add the/Add/ for brevity.

On Tue, Apr 30, 2024 at 10:37:24AM +0200, Herve Codina wrote:
> PCI devices and bridges DT nodes created during the PCI scan are created
> with the interrupt-map property set to handle interrupts.
>
> In order to set this interrupt-map property at a specific level, a
> phandle to the parent interrupt controller is needed.
> On systems that are not fully described by a device-tree, the parent
> interrupt controller may be unavailable (i.e. not described by the
> device-tree).

Rewrap into one paragraph or add blank line to separate paragraphs.

> As mentioned in the [1], avoiding the use of the interrupt-map property
> and considering a PCI device as an interrupt controller itself avoid the
> use of a parent interrupt phandle.
>
> In that case, the PCI device itself as an interrupt controller is
> responsible for routing the interrupts described in the device-tree
> world (DT overlay) to the PCI interrupts.
>
> Add the 'interrupt-controller' property in the PCI device DT node.
>
> [1]: https://lore.kernel.org/lkml/CAL_Jsq+je7+9ATR=B6jXHjEJHjn24vQFs4Tvi9=vhDeK9n42Aw@xxxxxxxxxxxxxx/
>
> Signed-off-by: Herve Codina <herve.codina@xxxxxxxxxxx>
> ---
> drivers/pci/of_property.c | 24 ++++++++++++++++++++++++
> 1 file changed, 24 insertions(+)
>
> diff --git a/drivers/pci/of_property.c b/drivers/pci/of_property.c
> index c2c7334152bc..9f8b940029ed 100644
> --- a/drivers/pci/of_property.c
> +++ b/drivers/pci/of_property.c
> @@ -183,6 +183,26 @@ static int of_pci_prop_interrupts(struct pci_dev *pdev,
> return of_changeset_add_prop_u32(ocs, np, "interrupts", (u32)pin);
> }
>
> +static int of_pci_prop_intr_ctrl(struct pci_dev *pdev, struct of_changeset *ocs,
> + struct device_node *np)
> +{
> + int ret;
> + u8 pin;
> +
> + ret = pci_read_config_byte(pdev, PCI_INTERRUPT_PIN, &pin);
> + if (ret != 0)
> + return ret;
> +
> + if (!pin)
> + return 0;
> +
> + ret = of_changeset_add_prop_u32(ocs, np, "#interrupt-cells", 1);
> + if (ret)
> + return ret;
> +
> + return of_changeset_add_prop_bool(ocs, np, "interrupt-controller");
> +}
> +
> static int of_pci_prop_intr_map(struct pci_dev *pdev, struct of_changeset *ocs,
> struct device_node *np)
> {
> @@ -334,6 +354,10 @@ int of_pci_add_properties(struct pci_dev *pdev, struct of_changeset *ocs,
> ret = of_pci_prop_intr_map(pdev, ocs, np);
> if (ret)
> return ret;
> + } else {
> + ret = of_pci_prop_intr_ctrl(pdev, ocs, np);
> + if (ret)
> + return ret;
> }
>
> ret = of_pci_prop_ranges(pdev, ocs, np);
> --
> 2.44.0
>