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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 E603FC433E0 for ; Thu, 4 Mar 2021 04:10:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id ABB9A64EEF for ; Thu, 4 Mar 2021 04:10:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233196AbhCDEJo (ORCPT ); Wed, 3 Mar 2021 23:09:44 -0500 Received: from szxga04-in.huawei.com ([45.249.212.190]:12682 "EHLO szxga04-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232892AbhCDEJg (ORCPT ); Wed, 3 Mar 2021 23:09:36 -0500 Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga04-in.huawei.com (SkyGuard) with ESMTP id 4DrckX3KpzzlSPm; Thu, 4 Mar 2021 12:06:44 +0800 (CST) Received: from [10.67.102.118] (10.67.102.118) by DGGEMS402-HUB.china.huawei.com (10.3.19.202) with Microsoft SMTP Server id 14.3.498.0; Thu, 4 Mar 2021 12:08:43 +0800 Subject: Re: [RFC PATCH] USB:XHCI:Modify XHCI driver for USB2.0 controller To: Peter Chen CC: Greg KH , , , , References: <1614327697-1021-1-git-send-email-liulongfang@huawei.com> <87cc8b54-f530-cce0-3ea2-f879436ff5f7@huawei.com> <20210304013548.GA16596@nchen> From: liulongfang Message-ID: Date: Thu, 4 Mar 2021 12:08:43 +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: <20210304013548.GA16596@nchen> Content-Type: text/plain; charset="gbk" Content-Transfer-Encoding: 8bit X-Originating-IP: [10.67.102.118] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/3/4 9:35, Peter Chen wrote: > On 21-02-27 11:31:00, liulongfang wrote: >> On 2021/2/26 16:38, Greg KH wrote: >>> On Fri, Feb 26, 2021 at 04:21:37PM +0800, Longfang Liu wrote: >>>> Our current XHCI hardware controller has been customized to only >>>> support USB 2.0 ports. >>> >>> That sounds like a spec violation, right? Why do you want to do this? >>> >>> greg k-h >>> . >>> >> I hope to support a USB2.0-only mode on the XHCI controller >> through software configuration. >> Thanks. > > If your hardware has disabled USB3 logic, when the USB3 device is plugged, > since there are no RX signal on the bus, the device will not enable USB3 > logic, and only USB2 signals will be on the bus, there are only USB devices on > USB2 roothub later. So, any issues you have met? > I don¡¯t want to see the USB3 bus controller in the system, but it actually exists. Thanks. Longfang, Liu