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_HELO_NONE,SPF_PASS 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 1DB17C06511 for ; Tue, 2 Jul 2019 13:14:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EA91F2064B for ; Tue, 2 Jul 2019 13:14:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727017AbfGBNOH convert rfc822-to-8bit (ORCPT ); Tue, 2 Jul 2019 09:14:07 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:2962 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726375AbfGBNOH (ORCPT ); Tue, 2 Jul 2019 09:14:07 -0400 Received: from DGGEMM402-HUB.china.huawei.com (unknown [172.30.72.53]) by Forcepoint Email with ESMTP id 691112B14BA1ABE84440; Tue, 2 Jul 2019 21:14:04 +0800 (CST) Received: from dggeme765-chm.china.huawei.com (10.3.19.111) by DGGEMM402-HUB.china.huawei.com (10.3.20.210) with Microsoft SMTP Server (TLS) id 14.3.439.0; Tue, 2 Jul 2019 21:14:03 +0800 Received: from dggeme763-chm.china.huawei.com (10.3.19.109) by dggeme765-chm.china.huawei.com (10.3.19.111) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1591.10; Tue, 2 Jul 2019 21:14:03 +0800 Received: from dggeme763-chm.china.huawei.com ([10.6.66.36]) by dggeme763-chm.china.huawei.com ([10.6.66.36]) with mapi id 15.01.1591.008; Tue, 2 Jul 2019 21:14:03 +0800 From: linmiaohe To: Lukas Wunner CC: "bhelgaas@google.com" , "andy.shevchenko@gmail.com" , "rafael.j.wysocki@intel.com" , "linux-pci@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Mingfangsen Subject: Re: A question about shpcp. Thread-Topic: A question about shpcp. Thread-Index: AdUw1y6s60N5MVYrQQefLwWPyJccGQ== Date: Tue, 2 Jul 2019 13:14:03 +0000 Message-ID: Accept-Language: en-US Content-Language: zh-CN X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.184.189.20] Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, July 2, 2019 at 20:21:18PM +0000, Lukas wrote: > On Thu, Jun 27, 2019 at 12:16:18PM +0000, linmiaohe wrote: > > It's very nice of you if you could tell me why is 5*HZ there and if > > this delay can be reduced? > > According to Table 2-4 of the PCI Standard Hot-Plug Controller and Subsystem Specification, "System software is waiting 5 seconds to provide the user with an opportunity to cancel the hot-plug operation." > (http://drydkim.com/MyDocuments/PCI%20Spec/specifications/shpc1_0.pdf) > > So the reason the delay can't be reduced or removed is because the spec mandates it. > > Thanks, > > Lukas Many thanks for explaining this. Thanks a lot. Have a nice day. Best wishes.