Re: [PATCH] USB: OHCI/UHCI: Add soft dependencies on ehci_platform

[Alan Stern]

On Mon, Jan 12, 2026 at 04:48:02PM +0800, Huacai Chen wrote:
> Commit 9beeee6584b9aa4f ("USB: EHCI: log a warning if ehci-hcd is not
> loaded first") said that ehci-hcd should be loaded before ohci-hcd and
> uhci-hcd. However, commit 05c92da0c52494ca ("usb: ohci/uhci - add soft
> dependencies on ehci_pci") only makes ohci-pci/uhci-pci depend on ehci-
> pci, which is not enough and we may still see the warnings in boot log.
> 
> To eliminate the warnings we should make ohci-hcd/uhci-hcd depend on
> ehci-hcd. But Alan said that the warning introduced by 9beeee6584b9aa4f
> is bogus, we only need the soft dependencies in the PCI level rather
> than the HCD level.
> 
> However, there is really another neccessary soft dependencies between
> ohci-platform/uhci-platform and ehci-platform, which is added by this
> patch. The boot logs are below.
> 
> 1. ohci-platform loaded before ehci-platform:
> 
>  ohci-platform 1f058000.usb: Generic Platform OHCI controller
>  ohci-platform 1f058000.usb: new USB bus registered, assigned bus number 1
>  ohci-platform 1f058000.usb: irq 28, io mem 0x1f058000
>  hub 1-0:1.0: USB hub found
>  hub 1-0:1.0: 4 ports detected
>  Warning! ehci_hcd should always be loaded before uhci_hcd and ohci_hcd, not after
>  usb 1-4: new low-speed USB device number 2 using ohci-platform
>  ehci-platform 1f050000.usb: EHCI Host Controller
>  ehci-platform 1f050000.usb: new USB bus registered, assigned bus number 2
>  ehci-platform 1f050000.usb: irq 29, io mem 0x1f050000
>  ehci-platform 1f050000.usb: USB 2.0 started, EHCI 1.00
>  usb 1-4: device descriptor read/all, error -62
>  hub 2-0:1.0: USB hub found
>  hub 2-0:1.0: 4 ports detected
>  usb 1-4: new low-speed USB device number 3 using ohci-platform
>  input: YSPRINGTECH USB OPTICAL MOUSE as /devices/platform/bus@10000000/1f058000.usb/usb1/1-4/1-4:1.0/0003:10C4:8105.0001/input/input0
>  hid-generic 0003:10C4:8105.0001: input,hidraw0: USB HID v1.11 Mouse [YSPRINGTECH USB OPTICAL MOUSE] on usb-1f058000.usb-4/input0
> 
> 2. ehci-platform loaded before ohci-platform:
> 
>  ehci-platform 1f050000.usb: EHCI Host Controller
>  ehci-platform 1f050000.usb: new USB bus registered, assigned bus number 1
>  ehci-platform 1f050000.usb: irq 28, io mem 0x1f050000
>  ehci-platform 1f050000.usb: USB 2.0 started, EHCI 1.00
>  hub 1-0:1.0: USB hub found
>  hub 1-0:1.0: 4 ports detected
>  ohci-platform 1f058000.usb: Generic Platform OHCI controller
>  ohci-platform 1f058000.usb: new USB bus registered, assigned bus number 2
>  ohci-platform 1f058000.usb: irq 29, io mem 0x1f058000
>  hub 2-0:1.0: USB hub found
>  hub 2-0:1.0: 4 ports detected
>  usb 2-4: new low-speed USB device number 2 using ohci-platform
>  input: YSPRINGTECH USB OPTICAL MOUSE as /devices/platform/bus@10000000/1f058000.usb/usb2/2-4/2-4:1.0/0003:10C4:8105.0001/input/input0
>  hid-generic 0003:10C4:8105.0001: input,hidraw0: USB HID v1.11 Mouse [YSPRINGTECH USB OPTICAL MOUSE] on usb-1f058000.usb-4/input0
> 
> In the later case, there is no re-connection for USB-1.0/1.1 devices,
> which is expected.
> 
> Cc: stable@xxxxxxxxxxxxxxx
> Reported-by: Shengwen Xiao <atzlinux@xxxxxxxx>
> Signed-off-by: Huacai Chen <chenhuacai@xxxxxxxxxxx>
> ---

Reviewed-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>

>  drivers/usb/host/ohci-platform.c | 1 +
>  drivers/usb/host/uhci-platform.c | 1 +
>  2 files changed, 2 insertions(+)
> 
> diff --git a/drivers/usb/host/ohci-platform.c b/drivers/usb/host/ohci-platform.c
> index 2e4bb5cc2165..c801527d5bd2 100644
> --- a/drivers/usb/host/ohci-platform.c
> +++ b/drivers/usb/host/ohci-platform.c
> @@ -392,3 +392,4 @@ MODULE_DESCRIPTION(DRIVER_DESC);
>  MODULE_AUTHOR("Hauke Mehrtens");
>  MODULE_AUTHOR("Alan Stern");
>  MODULE_LICENSE("GPL");
> +MODULE_SOFTDEP("pre: ehci_platform");
> diff --git a/drivers/usb/host/uhci-platform.c b/drivers/usb/host/uhci-platform.c
> index 5e02f2ceafb6..f4419d4526c4 100644
> --- a/drivers/usb/host/uhci-platform.c
> +++ b/drivers/usb/host/uhci-platform.c
> @@ -211,3 +211,4 @@ static struct platform_driver uhci_platform_driver = {
>  		.of_match_table = platform_uhci_ids,
>  	},
>  };
> +MODULE_SOFTDEP("pre: ehci_platform");
> -- 
> 2.47.3
>