From: liulongfang <liulongfang@huawei.com>
To: Alan Stern <stern@rowland.harvard.edu>
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 11:11:01 +0800 [thread overview]
Message-ID: <1abf8a09-4209-e000-f608-8664a4964670@huawei.com> (raw)
In-Reply-To: <20210416152021.GA42403@rowland.harvard.edu>
On 2021/4/16 23:20, Alan Stern wrote:
> On Fri, Apr 16, 2021 at 10:03:21AM +0800, liulongfang wrote:
>> On 2021/4/15 22:43, Alan Stern wrote:
>>> On Thu, Apr 15, 2021 at 08:22:38PM +0800, Longfang Liu wrote:
>>>> When the number of ports on the USB hub is 0, skip the registration
>>>> operation of the USB hub.
>>>>
>>>> The current Kunpeng930's XHCI hardware controller is defective. The number
>>>> of ports on its USB3.0 bus controller is 0, and the number of ports on
>>>> the USB2.0 bus controller is 1.
>>>>
>>>> In order to solve this problem that the USB3.0 controller does not have
>>>> a port which causes the registration of the hub to fail, this patch passes
>>>> the defect information by adding flags in the quirks of xhci and usb_hcd,
>>>> and finally skips the registration process of the hub directly according
>>>> to the results of these flags when the hub is initialized.
>>>>
>>>> Signed-off-by: Longfang Liu <liulongfang@huawei.com>
>>>
>>> The objections that Greg raised are all good ones.
>>>
>>> But even aside from them, this patch doesn't actually do what the
>>> description says. The patch doesn't remove the call to usb_add_hcd
>>> for the USB-3 bus. If you simply skipped that call (and the
>>> corresponding call to usb_remove_hcd) when there are no
>>> ports on the root hub, none of the stuff in this patch would be needed.
>>>
>>> Alan Stern
>>>
>>
>> "[RFC PATCH] USB:XHCI:Adjust the log level of hub"
>
> I don't understand. What patch is that? Do you have a URL for it?
>
URL: https://patchwork.kernel.org/project/linux-usb/patch/1616666652-37920-1-git-send-email-liulongfang@huawei.com/
Thanks
Longfang.
>> 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.
>
>> after skipping registering, no port will not report error log,the goal of this
>> patch is reached without error log output.
>
> Why do you want to get rid of the error log output? There really _is_
> an error, because the USB-3 hardware on your controller is defective.
> Since the hardware is buggy, we _should_ print an error message in the
> kernel log.
>
> Alan Stern
> .
>
next prev parent reply other threads:[~2021-04-17 3:11 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 [this message]
2021-04-17 6:48 ` liulongfang
2021-04-17 15:31 ` Alan Stern
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