Re: [PATCH v2 1/4] PCI: rcar-gen4: Configure AXIINTC if iMSI-RX not used

[Geert Uytterhoeven]

Hi Marek, Shimoda-san,

On Fri, 19 Jun 2026 at 00:04, Marek Vasut
<marek.vasut+renesas@xxxxxxxxxxx> wrote:
> In case MSI are enabled, but DWC built-in iMSI-RX is not in use, the
> MSI are handled via GIC ITS. Configure all controller MSI registers
> fully.
>
> Set or clear MSI capability register MSICAP0 MSI enable MSIE bit and
> PCIe Interrupt Status 0 Enable register PCIEINTSTS0EN MSI interrupt
> enable MSI_CTRL_INT bit according to MSI enable state, set both bits
> if MSI are enabled, clear both bits if MSI are disabled.
>
> If MSI are disabled, or MSI are enabled and iMSI-RX is used, then
> deconfigure AXIINTCADDR and AXIINTCCONT to 0, which disables any
> pass through of MSI TLPs onto the AXI bus and then further into
> GIC ITS translation registers.
>
> If MSI are enabled and iMSI-RX is not used, the configure AXIINTCADDR
> with target address of GIC ITS translation registers, and configure
> AXIINTCCONT to enable MSI TLP pass through onto AXI bus and into the
> GIC ITS. This specific configuration allows handling of MSI via the
> GIC ITS instead of integrated iMSI-RX.
>
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
> Signed-off-by: Marek Vasut <marek.vasut+renesas@xxxxxxxxxxx>

Thanks for your patch!

> --- a/drivers/pci/controller/dwc/pcie-rcar-gen4.c
> +++ b/drivers/pci/controller/dwc/pcie-rcar-gen4.c

> @@ -305,13 +320,103 @@ static struct rcar_gen4_pcie *rcar_gen4_pcie_alloc(struct platform_device *pdev)
>         return rcar;
>  }
>
> +static int rcar_gen4_pcie_host_msi_addr(struct dw_pcie_rp *pp, u32 *msi_addr)
> +{
> +       struct dw_pcie *dw = to_dw_pcie_from_pp(pp);
> +       struct device_node *msi_node = NULL;
> +       struct device *dev = dw->dev;
> +       struct resource res;
> +       u64 addr;
> +       int ret;
> +
> +       /*
> +        * Either the "msi-parent" or the "msi-map" phandle needs to exist
> +        * to obtain the MSI node.
> +        */
> +       of_msi_xlate(dev, &msi_node, 0);
> +       if (!msi_node)
> +               return -ENODEV;

This is not backwards-compatible with existing DTBs.
I noticed because PCIe is broken on Gray Hawk Single with R-Car V4M
after this series.  Indeed, "[PATCH v2 4/4] arm64: dts: renesas:
r8a779g0: Add GICv3 ITS and update PCIe nodes" only covers R-Car V4H,
but not R-Car S4-8 and R-Car V4M.

> +
> +       /* Check if "msi-parent" or the "msi-map" points to ARM GICv3 ITS. */
> +       if (!of_device_is_compatible(msi_node, "arm,gic-v3-its"))
> +               return dev_err_probe(dev, -ENODEV, "Compatible MSI controller not found\n");
> +
> +       /* Derive GITS_TRANSLATER address from GICv3 */
> +       ret = of_address_to_resource(msi_node, 0, &res);
> +       if (ret < 0)
> +               return dev_err_probe(dev, ret, "MSI controller resources not obtained\n");
> +
> +       addr = res.start + GITS_TRANSLATER;
> +       if (addr >= SZ_4G)
> +               return dev_err_probe(dev, -EINVAL, "MSI controller address above 32bit range\n");
> +
> +       *msi_addr = addr;
> +       return 0;
> +}

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds