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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 BDE42C433E0 for ; Tue, 23 Jun 2020 08:35:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A8197206D4 for ; Tue, 23 Jun 2020 08:35:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731875AbgFWIfd (ORCPT ); Tue, 23 Jun 2020 04:35:33 -0400 Received: from mga12.intel.com ([192.55.52.136]:33318 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731567AbgFWIfb (ORCPT ); Tue, 23 Jun 2020 04:35:31 -0400 IronPort-SDR: 6iQP/UTYKWsWsUAckOwjhIfQBLMdbUxiagy/RPo8Wz8jOC3d8s/vtzcr8eMOsdnyIBiOb8XgM3 XvHgsQu+CjCA== X-IronPort-AV: E=McAfee;i="6000,8403,9660"; a="123671419" X-IronPort-AV: E=Sophos;i="5.75,270,1589266800"; d="scan'208";a="123671419" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 23 Jun 2020 01:35:30 -0700 IronPort-SDR: rFRootrZkIH0vya6Z3UizkgS5DSC2GOJujVhlZnezKonup3YqFAvhQsL6cQmp4YqA6g64LQREL UBLBL2HBcaXg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,270,1589266800"; d="scan'208";a="310388231" Received: from mattu-haswell.fi.intel.com (HELO [10.237.72.170]) ([10.237.72.170]) by orsmga008.jf.intel.com with ESMTP; 23 Jun 2020 01:35:28 -0700 Subject: Re: [PATCH 2/2] xhci: Poll for U0 after disabling USB2 LPM To: Kai-Heng Feng Cc: Mathias Nyman , Greg Kroah-Hartman , "open list:USB XHCI DRIVER" , open list References: <20200520101811.2623-1-kai.heng.feng@canonical.com> <20200520101811.2623-2-kai.heng.feng@canonical.com> <6c3ac2e5-73e9-6e4f-2940-63403821631f@linux.intel.com> <8327233C-5DE8-43F8-9208-5FF888629047@canonical.com> <9FC0BA5C-4D00-4D33-B040-AA5584A8E9A6@canonical.com> From: Mathias Nyman Openpgp: preference=signencrypt Autocrypt: addr=mathias.nyman@linux.intel.com; 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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <9FC0BA5C-4D00-4D33-B040-AA5584A8E9A6@canonical.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 19.6.2020 17.19, Kai-Heng Feng wrote: > Hi Mathias, > >> On Jun 9, 2020, at 18:15, Kai-Heng Feng wrote: >> >> >> >>> On Jun 8, 2020, at 19:21, Mathias Nyman wrote: >>> >>> On 20.5.2020 13.18, Kai-Heng Feng wrote: >>>> USB2 devices with LPM enabled may interrupt the system suspend: >>>> [ 932.510475] usb 1-7: usb suspend, wakeup 0 >>>> [ 932.510549] hub 1-0:1.0: hub_suspend >>>> [ 932.510581] usb usb1: bus suspend, wakeup 0 >>>> [ 932.510590] xhci_hcd 0000:00:14.0: port 9 not suspended >>>> [ 932.510593] xhci_hcd 0000:00:14.0: port 8 not suspended >>>> .. >>>> [ 932.520323] xhci_hcd 0000:00:14.0: Port change event, 1-7, id 7, portsc: 0x400e03 >>> >>> 400e03 = Connected, Enabled, U0 with port ink state change flag (PLC) set. >>> >>>> .. >>>> [ 932.591405] PM: pci_pm_suspend(): hcd_pci_suspend+0x0/0x30 returns -16 >>>> [ 932.591414] PM: dpm_run_callback(): pci_pm_suspend+0x0/0x160 returns -16 >>>> [ 932.591418] PM: Device 0000:00:14.0 failed to suspend async: error -16 >>>> >>>> During system suspend, USB core will let HC suspends the device if it >>>> doesn't have remote wakeup enabled and doesn't have any children. >>>> However, from the log above we can see that the usb 1-7 doesn't get bus >>>> suspended due to not in U0. After a while the port finished U2 -> U0 >>>> transition, interrupts the suspend process. >>> >>> In USB2 HW link PM the PLC flag should not be set in U2Exit -> U0 transitions. >>> Only case we should see a port change event is U2Entry -> U0 due to STALL or >>> error/timeout. (see xhci 4.23.5.1.1.1) >>> >>>> >>>> The observation is that after disabling LPM, port doesn't transit to U0 >>>> immediately and can linger in U2. xHCI spec 4.23.5.2 states that the >>>> maximum exit latency for USB2 LPM should be BESL + 10us. The BESL for >>>> the affected device is advertised as 400us, which is still not enough >>>> based on my testing result. >>>> >>>> So let's use the maximum permitted latency, 10000, to poll for U0 >>>> status to solve the issue. >>> >>> I don't recall all details, but it could be that disabling LPM before suspend >>> is unnecessary. >>> At least xhci should be able to set a port to U3 from U1 and U2 (see xhci 4.15.1) >>> so that is one change that could be done to xhci_bus_suspend() >> >> Yes, put the device to U3 directly does the trick. > > As discussed, will you pick this series over the v2? > Or is there anything I should improve for this one? > > Kai-Heng Added this to queueI Thanks -Mathias