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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6CDFBC433EF for ; Wed, 16 Mar 2022 02:18:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345211AbiCPCUC (ORCPT ); Tue, 15 Mar 2022 22:20:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34428 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236034AbiCPCUA (ORCPT ); Tue, 15 Mar 2022 22:20:00 -0400 Received: from ZXSHCAS1.zhaoxin.com (ZXSHCAS1.zhaoxin.com [203.148.12.81]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1AA7339B85; Tue, 15 Mar 2022 19:18:45 -0700 (PDT) Received: from zxbjmbx1.zhaoxin.com (10.29.252.163) by ZXSHCAS1.zhaoxin.com (10.28.252.161) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.20; Wed, 16 Mar 2022 10:18:42 +0800 Received: from [10.29.8.53] (10.29.8.53) by zxbjmbx1.zhaoxin.com (10.29.252.163) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.20; Wed, 16 Mar 2022 10:18:40 +0800 Subject: Re: [PATCH] USB:Fix ehci infinite suspend-resume loop issue in zhaoxin To: Alan Stern CC: , , , , , , References: <3d0ae3ca-9dad-bb8f-5c41-45bdcb07b9cd@zhaoxin.com> <320584eb-ef89-3759-509c-e7e9cb10f983@zhaoxin.com> From: "WeitaoWang-oc@zhaoxin.com" Message-ID: Date: Wed, 16 Mar 2022 10:18:39 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.29.8.53] X-ClientProxiedBy: ZXSHCAS1.zhaoxin.com (10.28.252.161) To zxbjmbx1.zhaoxin.com (10.29.252.163) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/3/15 11:18, Alan Stern wrote: > On Tue, Mar 15, 2022 at 08:39:09PM +0800, WeitaoWang-oc@zhaoxin.com wrote: >> On 2022/3/14 10:24, Alan Stern wrote: >>>> + t1 = ehci_readl(ehci, &ehci->regs->status); >>>> + ehci_writel(ehci, t1 & STS_PCD, &ehci->regs->status); >>>> + ehci_readl(ehci, &ehci->regs->status); >>> >>> You should not clear the STS_PCD bit. What if some other port had a >>> status change at the same time? Then because you cleared the >>> port-change-detect bit, the system would not realize that the other port >>> needed to be handled. >> >> I really didn't think about this case. >> >>> Leaving the STS_PCD bit turned on will cause the driver to do a little >>> extra work, but it shouldn't cause any harm. >>> >> I have encountered the following situation if EHCI runtime suspend is >> enabled by default. >> >> >> >> 1.Wake from system to disk and boot OS. > > You're talking about resuming after hibernation, right? You're right. >> 2.EHCI will entry runtime suspend after enumerated by driver during boot >> phase of suspend to disk > > I'm not sure what you mean by "boot phase of suspend to disk". This is > while the restore kernel is starting up at the beginning of resume from > hibernation, right? > You understood exactly what I was saying. >> 3.EHCI will be placed to freeze state and ehci_resume is called after image >> is loaded. > > ehci_resume is called to leave runtime suspend. Going into the freeze > state doesn't require any changes. > >> 4.If PCD flag is set(caused by patch), then HCD_FLAG_RH_RUNNING will be set. >> >> 5.Pci_pm_freeze_noirq is called to check ehci root hub state and return >> value is -EBUSY. which will cause >> quiesce phase of suspend to disk fail. > > You're talking about check_root_hub_suspended() in hcd-pci.c, right? > It's right. > You know, I'm not at all certain that the callbacks for freeze and > freeze_noirq should ever return anything other than 0. It's okay for > them to call check_root_hub_suspended(), but they should ignore its > return value. > > Can you check if the patch below helps? > > Alan Stern > > > Index: usb-devel/drivers/usb/core/hcd-pci.c > =================================================================== > --- usb-devel.orig/drivers/usb/core/hcd-pci.c > +++ usb-devel/drivers/usb/core/hcd-pci.c > @@ -575,6 +575,12 @@ static int hcd_pci_resume(struct device > return resume_common(dev, PM_EVENT_RESUME); > } > > +static int hcd_pci_freeze_check(struct device *dev) > +{ > + (void) check_root_hub_suspended(dev); > + return 0; > +} > + > static int hcd_pci_restore(struct device *dev) > { > return resume_common(dev, PM_EVENT_RESTORE); > @@ -586,6 +592,7 @@ static int hcd_pci_restore(struct device > #define hcd_pci_suspend_noirq NULL > #define hcd_pci_resume_noirq NULL > #define hcd_pci_resume NULL > +#define hcd_pci_freeze_check NULL > #define hcd_pci_restore NULL > > #endif /* CONFIG_PM_SLEEP */ > @@ -616,8 +623,8 @@ const struct dev_pm_ops usb_hcd_pci_pm_o > .suspend_noirq = hcd_pci_suspend_noirq, > .resume_noirq = hcd_pci_resume_noirq, > .resume = hcd_pci_resume, > - .freeze = check_root_hub_suspended, > - .freeze_noirq = check_root_hub_suspended, > + .freeze = hcd_pci_freeze_check, > + .freeze_noirq = hcd_pci_freeze_check, This patch can fix pci driver's fail check in freeze_noirq phase. Restoring system state from a hibernation image can continue and success. Weitao Wang > .thaw_noirq = NULL, > .thaw = NULL, > .poweroff = hcd_pci_suspend, > . >