Re: [PATCH v2] PCI: dwc: rcar-gen4-ep: Mark BAR0 and BAR2 as Resizable BARs

[Bjorn Helgaas <helgaas@kernel.org>]

On Wed, Feb 11, 2026 at 01:03:15AM +0900, Koichiro Den wrote:
> R-Car Gen4 (S4) implements the PCIe Resizable BAR capability for BAR0 and
> BAR2. Advertise them as BAR_RESIZABLE so EPF-requested BAR sizes are
> reflected to the host.
> 
> Reviewed-by: Niklas Cassel <cassel@kernel.org>
> Signed-off-by: Koichiro Den <den@valinux.co.jp>
> ---
> Changes since v1:
>   - Reword commit message only, no code changes.
>   - Rebased onto pci/controller/dwc as of 2026-02-11
> 
> v1: https://lore.kernel.org/linux-pci/20251023072217.901888-1-den@valinux.co.jp
> 
>  drivers/pci/controller/dwc/pcie-rcar-gen4.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-rcar-gen4.c b/drivers/pci/controller/dwc/pcie-rcar-gen4.c
> index a6912e85e4dd..3d4a889e38cc 100644
> --- a/drivers/pci/controller/dwc/pcie-rcar-gen4.c
> +++ b/drivers/pci/controller/dwc/pcie-rcar-gen4.c
> @@ -422,7 +422,9 @@ static int rcar_gen4_pcie_ep_raise_irq(struct dw_pcie_ep *ep, u8 func_no,
>  static const struct pci_epc_features rcar_gen4_pcie_epc_features = {
>  	DWC_EPC_COMMON_FEATURES,
>  	.msi_capable = true,
> +	.bar[BAR_0] = { .type = BAR_RESIZABLE, },
>  	.bar[BAR_1] = { .type = BAR_RESERVED, },
> +	.bar[BAR_2] = { .type = BAR_RESIZABLE, },

I guess the "Resizable" property is not something that is discoverable
at runtime?

You mention the Resizable BAR Capability, so I wondered if the driver
could use that to figure this out.

 * @BAR_RESIZABLE: The BAR implements the PCI-SIG Resizable BAR Capability.
 *                 NOTE: An EPC driver can currently only set a single supported
 *                 size.

Is this comment about the single supported size still accurate?

>  	.bar[BAR_3] = { .type = BAR_RESERVED, },
>  	.bar[BAR_4] = { .type = BAR_FIXED, .fixed_size = 256 },
>  	.bar[BAR_5] = { .type = BAR_RESERVED, },
> -- 
> 2.51.0
>