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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 46112C43219 for ; Mon, 29 Apr 2019 02:33:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 12977206BF for ; Mon, 29 Apr 2019 02:33:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727172AbfD2CdO (ORCPT ); Sun, 28 Apr 2019 22:33:14 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:53072 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726819AbfD2CdO (ORCPT ); Sun, 28 Apr 2019 22:33:14 -0400 Received: from DGGEMS405-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 7961D2ADFCC4B4BEFE0E; Mon, 29 Apr 2019 10:33:12 +0800 (CST) Received: from [127.0.0.1] (10.67.78.74) by DGGEMS405-HUB.china.huawei.com (10.3.19.205) with Microsoft SMTP Server id 14.3.439.0; Mon, 29 Apr 2019 10:33:08 +0800 Subject: Re: [RFC] Question about reset order for xhci controller and pci To: , , , References: <4ae9963b-cfc1-7667-6082-a979725af0eb@huawei.com> From: "Tangnianyao (ICT)" Message-ID: <160fa1ea-2e82-343b-d5d6-2b9adde70cf4@huawei.com> Date: Mon, 29 Apr 2019 10:33:08 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.0 MIME-Version: 1.0 In-Reply-To: <4ae9963b-cfc1-7667-6082-a979725af0eb@huawei.com> Content-Type: text/plain; charset="gbk" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.78.74] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Using command "echo 1 > /sys/bus/pci/devices/0000:7a:02.0/reset" on centos7.5 system to reset xhci. On 2019/4/26 11:07, Tangnianyao (ICT) wrote: > Hi,all > > I've meet a problem about reset xhci and it may be caused by the > reset order of pci and xhci. > Using xhci-pci, when users send reset command in os(centos or red-hat os), > it would first reset PCI device by pci_reset_function. During this > process, it would disable BME(Bus Master Enable) and set BME=0, and > then enable it and set BME=1. > And then it comes to xhci reset process. First, it would send an > endpoint stop command in xhci_urb_dequeue. However, this stop ep command > fails to finish. The reason is that BME is set to 0 in former process and > xhci RUN/STOP changes to 0, and when BME is set to 1 again, RUN/STOP doesn't > recover to 1. > I've checked BME behavior in xhci spec, it shows that "If the BME bit is set to 0 > when xHC is running, the xHC may treat this as a Host Controller Error, asserting > HCE(1) and immediately halt(R/S=0 and HCH=1). Recovery from this state will > require an HCRST." It seems that the stop ep command failure is reasonable. > Maybe I've missed something and please let me know. > > linux version:5.0.0-rc3 > > Thanks, > Nianyao Tang > > > . >