From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0D1BCC433ED for ; Sat, 17 Apr 2021 03:11:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C81DF610CC for ; Sat, 17 Apr 2021 03:11:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235593AbhDQDLi (ORCPT ); Fri, 16 Apr 2021 23:11:38 -0400 Received: from szxga04-in.huawei.com ([45.249.212.190]:16133 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233847AbhDQDLh (ORCPT ); Fri, 16 Apr 2021 23:11:37 -0400 Received: from DGGEMS414-HUB.china.huawei.com (unknown [172.30.72.59]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4FMdLk2DlkzpYTh; Sat, 17 Apr 2021 11:08:14 +0800 (CST) Received: from [10.67.102.118] (10.67.102.118) by DGGEMS414-HUB.china.huawei.com (10.3.19.214) with Microsoft SMTP Server id 14.3.498.0; Sat, 17 Apr 2021 11:11:01 +0800 Subject: Re: [RFC PATCH] USB:XHCI:skip hub registration To: Alan Stern CC: , , , , , , References: <1618489358-42283-1-git-send-email-liulongfang@huawei.com> <20210415144323.GC1530055@rowland.harvard.edu> <3dad6f4f-6386-427c-c36c-7d26b9a76fa4@huawei.com> <20210416152021.GA42403@rowland.harvard.edu> From: liulongfang Message-ID: <1abf8a09-4209-e000-f608-8664a4964670@huawei.com> Date: Sat, 17 Apr 2021 11:11:01 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20210416152021.GA42403@rowland.harvard.edu> Content-Type: text/plain; charset="gbk" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.102.118] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 >>> >>> 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 > . >