From: Alan Stern <stern@rowland.harvard.edu>
To: liulongfang <liulongfang@huawei.com>
Cc: gregkh@linuxfoundation.org, mathias.nyman@intel.com,
liudongdong3@huawei.com, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org, kong.kongxinwei@hisilicon.com,
yisen.zhuang@huawei.com
Subject: Re: [RFC PATCH] USB:XHCI:skip hub registration
Date: Sat, 17 Apr 2021 11:31:04 -0400 [thread overview]
Message-ID: <20210417153104.GA73141@rowland.harvard.edu> (raw)
In-Reply-To: <547e07d6-ae62-1225-7483-754bf57ed1d2@huawei.com>
On Sat, Apr 17, 2021 at 02:48:22PM +0800, liulongfang wrote:
> On 2021/4/16 23:20, Alan Stern wrote:
> > On Fri, Apr 16, 2021 at 10:03:21AM +0800, liulongfang wrote:
> >> The current method is an improved method of the above patch.
> >> This patch just make it skip registering USB-3 root hub if that hub has no ports,
> >
> > No, that isn't what this patch does.
> >
> > If the root hub wasn't registered, hub_probe wouldn't get called. But
> > with your patch, the system tries to register the root hub, and it does
> > call hub_probe, and then that function fails with a warning message.
> >
> > The way to _really_ akip registering the root hub is to change the
> > xhci-hcd code. Make it skip calling usb_add_hcd.
> >
>
> If you do not register in the root hub, this will return an error code,
What will return an error code? Are you talking about xhci_pci_probe()?
You oight to be able to figure out how to make it work.
> which will make all the XHCI drivers unregister, causing the USB2.0 controllers
> on the xhci to be unavailable.
Alan Stern
prev parent reply other threads:[~2021-04-17 15:31 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-15 12:22 [RFC PATCH] USB:XHCI:skip hub registration Longfang Liu
2021-04-15 12:34 ` Greg KH
2021-04-16 2:43 ` liulongfang
2021-04-16 5:16 ` Greg KH
2021-04-15 14:43 ` Alan Stern
2021-04-16 2:03 ` liulongfang
2021-04-16 15:20 ` Alan Stern
2021-04-17 3:11 ` liulongfang
2021-04-17 6:48 ` liulongfang
2021-04-17 15:31 ` Alan Stern [this message]
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