linux-kernel - Re: [PATCH] USB: OHCI/UHCI: Add soft dependencies on ehci

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Message-Id: <DFBMNYF0U5PK.24YOAUZFZ0ESB@cknow-tech.com>
Date: Tue, 30 Dec 2025 15:40:27 +0100
From: "Diederik de Haas" <diederik@...ow-tech.com>
To: "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>, "Huacai Chen"
 <chenhuacai@...ngson.cn>
Cc: "Huacai Chen" <chenhuacai@...nel.org>, "Alan Stern"
 <stern@...land.harvard.edu>, <linux-usb@...r.kernel.org>,
 <linux-kernel@...r.kernel.org>, <stable@...r.kernel.org>, "Shengwen Xiao"
 <atzlinux@...a.com>, <linux-rockchip@...ts.infradead.org>
Subject: Re: [PATCH] USB: OHCI/UHCI: Add soft dependencies on ehci_hcd

On Tue Dec 30, 2025 at 9:15 AM CET, Greg Kroah-Hartman wrote:
> On Tue, Dec 30, 2025 at 04:00:14PM +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.
>> So fix it by also making ohci-hcd/uhci-hcd depend on ehci-hcd.
>> 
>> Cc: stable@...r.kernel.org
>> Reported-by: Shengwen Xiao <atzlinux@...a.com>
>> Signed-off-by: Huacai Chen <chenhuacai@...ngson.cn>
>> ---
>>  drivers/usb/host/ohci-hcd.c | 1 +
>>  drivers/usb/host/uhci-hcd.c | 1 +
>>  2 files changed, 2 insertions(+)
>> 
>> diff --git a/drivers/usb/host/ohci-hcd.c b/drivers/usb/host/ohci-hcd.c
>> index 9c7f3008646e..549c965b7fbe 100644
>> --- a/drivers/usb/host/ohci-hcd.c
>> +++ b/drivers/usb/host/ohci-hcd.c
>> @@ -1355,4 +1355,5 @@ static void __exit ohci_hcd_mod_exit(void)
>>  	clear_bit(USB_OHCI_LOADED, &usb_hcds_loaded);
>>  }
>>  module_exit(ohci_hcd_mod_exit);
>> +MODULE_SOFTDEP("pre: ehci_hcd");
>
> Ick, no, this way lies madness.  I hate the "softdep" stuff, it's
> usually a sign that something is wrong elsewhere.
>
> And don't add this _just_ to fix a warning message in a boot log, if you
> don't like that message, then build the module into your kernel, right?
>
> And I really should just go revert 05c92da0c524 ("usb: ohci/uhci - add
> soft dependencies on ehci_pci") as well, that feels wrong too.

FWIW, I've been seeing this warning on several of my Rockchip based
devices as well. I thought I had already mentioned that on some ML, but
couldn't find it on lore.k.o ... turns out I reported it on my 'own' ML:
https://lists.sr.ht/~diederik/pine64-discuss/%3CDD65LB64HB7K.15ZYRTB98X8G2@cknow.org%3E
(and likely on #linux-rockchip IRC channel)

Most of it is just my research notes, but the last post also had this:

```
I checked the last 20 boots on my devices to see that warning (or not).
Device				Number of times that warning showed up
Rock64 (rk3328)			16x
RockPro64 (rk3399)		11x
Quartz64 Model A (rk3566)	 7x
Quartz64 Model B (rk3566)	14x
PineTab2 (rk3566)		17x
NanoPi R5S (rk3568)		13x
Rock 5B (rk3588)		12x
```

While I generally don't like seeing warning messages, it often also
resulted in USB2 ports not working. Maybe even every time, but I only
notice it when I actually tried to use one of the USB2 ports.

The first post mentioned what I 'assume' to be the problem:
```
CONFIG_USB_XHCI_HCD=m
CONFIG_USB_EHCI_HCD=m
CONFIG_USB_OHCI_HCD=m
```

So I guess USB_EHCI_HCD doesn't work with '=m'.

Cheers,
  Diederik