Re: [RFC PATCH] usb: host: Default CONFIG_USB_XHCI_RCAR to module

[Lad, Prabhakar]

Hi Greg,

On Thu, May 7, 2026 at 5:20 PM Greg Kroah-Hartman
<gregkh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> On Thu, May 07, 2026 at 04:47:10PM +0100, Prabhakar wrote:
> > From: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> >
> > On R-Car Gen3 and RZ/G2HMNE SoCs, when CONFIG_USB_XHCI_RCAR is built-in
> > and the system boots with an NFS root filesystem, the xHCI controller
> > probes before firmware becomes available. As a result, the firmware
> > request fails:
> >
> >   xhci-renesas-hcd ee000000.usb: Direct firmware load for
> >   r8a779x_usb3_v3.dlmem failed with error -2
> >
> > Default CONFIG_USB_XHCI_RCAR to module on ARCH_RENESAS so that probing
> > is deferred until after the root filesystem is mounted, ensuring that
> > the firmware is accessible.
> >
> > Configurations explicitly selecting CONFIG_USB_XHCI_RCAR=y are
> > unaffected.
> >
> > Signed-off-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@xxxxxxxxxxxxxx>
> > ---
> >  drivers/usb/host/Kconfig | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/usb/host/Kconfig b/drivers/usb/host/Kconfig
> > index 0a277a07cf70..b70e019cc3ac 100644
> > --- a/drivers/usb/host/Kconfig
> > +++ b/drivers/usb/host/Kconfig
> > @@ -90,7 +90,7 @@ config USB_XHCI_RCAR
> >       tristate "xHCI support for Renesas R-Car SoCs"
> >       depends on USB_XHCI_PLATFORM
> >       depends on ARCH_RENESAS || COMPILE_TEST
> > -     default ARCH_RENESAS
> > +     default m if ARCH_RENESAS
>
> The module type here depends on your root filesystem.  If you are using
> nfs for your root, then you always know you need to properly build stuff
> into the kernel for modules that need firmware, this shouldn't be a
> default thing as NFS surely isn't a default system type anymore.
>
I agree. The module handling depends on the root filesystem setup.
I’ll drop this patch.

Cheers,
Prabhakar