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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAAhV-H7NGgHhrZ+oC2ZbzURj0--yVL8rpn4Z42xk9VzKD3E1Qw@mail.gmail.com>
Date: Sun, 11 Jan 2026 09:54:46 +0800
From: Huacai Chen <chenhuacai@...nel.org>
To: Alan Stern <stern@...land.harvard.edu>
Cc: Diederik de Haas <diederik@...ow-tech.com>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Huacai Chen <chenhuacai@...ngson.cn>, 
	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 Sat, Jan 10, 2026 at 11:00 PM Alan Stern <stern@...land.harvard.edu> wrote:
>
> On Sat, Jan 10, 2026 at 12:05:19PM +0800, Huacai Chen wrote:
> > So I think we need a softdep between ohci-platform/uhci-platform and
> > ehci-platform, which is similar to the PCI case.
>
> Yes, on your platform.  But not on other platforms.  (For example, not
> on a platform that doesn't have an EHCI controller.)
For the PCI case, OHCI without EHCI is also possible? So I think they
are similar.

>
> I think the best way to do this is to create a new CONFIG_EHCI_SOFTDEPS
> Kconfig symbol, and add the soft dependency only if the symbol is
> defined.  Normally it will be undefined by default, but on your platform
> (and any others that need it) you can select it.
>
> How does that sound?
>From my point of view, keeping it simple may be better. I think an
unconditional softdep is harmless.

>
> > > There are other issues involving companion controllers, connected with
> > > hibernation.  You should take a look at commit 6d19c009cc78 ("USB:
> > > implement non-tree resume ordering constraints for PCI host
> > > controllers"), which was later modified by commit 05768918b9a1 ("USB:
> > > improve port transitions when EHCI starts up") and a few others.
> > >
> > > Also, read through the current code in hcd-pci.c (for_each_companion(),
> > > ehci_pre_add(), ehci_post_add(), non_ehci_add(), ehci_remove(), and
> > > ehci_wait_for_companions()).  Your non-PCI system will need to implement
> > > some sort of equivalent to all these things.
> > At least for the device probe, a softdep seems enough.
>
> Does this platform support hibernation at all?
LS2K500 is an embedded chip, it may or may not support hibernation,
but we haven't used hibernation.

Huacai

>
> Alan Stern