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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2176DC433F5 for ; Sat, 9 Oct 2021 19:39:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EF21C60F94 for ; Sat, 9 Oct 2021 19:39:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229926AbhJITlA (ORCPT ); Sat, 9 Oct 2021 15:41:00 -0400 Received: from netrider.rowland.org ([192.131.102.5]:50935 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S229558AbhJITk7 (ORCPT ); Sat, 9 Oct 2021 15:40:59 -0400 Received: (qmail 754485 invoked by uid 1000); 9 Oct 2021 15:39:01 -0400 Date: Sat, 9 Oct 2021 15:39:01 -0400 From: Alan Stern To: zhuyinbo Cc: Greg Kroah-Hartman , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Patchwork Bot Subject: Re: [PATCH v3] usb: ohci: add check for host controller functional states Message-ID: <20211009193901.GA753830@rowland.harvard.edu> References: <1633677970-10619-1-git-send-email-zhuyinbo@loongson.cn> <20211008142639.GA721194@rowland.harvard.edu> <7a505fc4-ec47-ac83-633f-7a5251bd5f82@loongson.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <7a505fc4-ec47-ac83-633f-7a5251bd5f82@loongson.cn> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Sat, Oct 09, 2021 at 10:01:25AM +0800, zhuyinbo wrote: > > 在 2021/10/8 下午10:26, Alan Stern 写道: > > On Fri, Oct 08, 2021 at 03:26:10PM +0800, Yinbo Zhu wrote: > > > The usb states of ohci controller include UsbOperational, UsbReset, > > > UsbSuspend and UsbResume. Among them, only the UsbOperational state > > > supports launching the start of frame for host controller according > > > the ohci protocol spec, but in S3/S4 press test procedure, it may > > Nobody reading this will know what "S3/S4 press test procedure" means. > > You have to explain it, or use a different name that people will > > understand. > okay, I got it. > > > happen that the start of frame was launched in other usb states and > > > cause ohci works abnormally then kernel will allways report rcu > > > call trace. This patch was to add check for host controller > > > functional states and if it is not UsbOperational state that need > > > set INTR_SF in intrdisable register to ensure SOF Token generation > > > was been disabled. > > This doesn't make sense. You already mentioned that only the > > UsbOperational state supports sending start-of-frame packets. So if the > > controller is in a different state then it won't send these packets, > > whether INTR_SF is enabled or not. > > > > What problem are you really trying to solve? > > Only UsbOperational state supports sending start-of-frame packets, but in > fact, in S3/S4 press test procedure, > > usb in non-UsbOperational state that send start-of-frame packets but hc > driver doesn't deal with this frame. and hc will > > allways lauched the SOF for finishing the frame, the cpu will hand this sof > interrupt and doesn't deal with time interrupt > > that will cause rcu call trace then system doesn't suspend to memory/disk. I still don't understand. Are you saying that your OHCI controller behaves badly because it sends SOF packets even when the state is different from UsbOperational? > Hi Alan Stern, > >     even though ed_rm_list is non-NULL, if hc in non-UsbOperation state set > SoF status in usbsts register that is illegal, > > at this time hcd doesn't need care URB whether finished,  because hc had > into a wrong state. even thoug it doesn't has this patch, > > URB was not be able to finish when hc in above worng state. except software > can intervence this wrong state. but the SoF bit of usbsts > > register was set by HC, and this action will happen always !!! software > clear SoF state I think it isn't make sense. software only disable SoF > > interrupt to fix HC wrong state. This problem happens when you go into S3 or S4 suspend, right? So you should fix the problem by disabling INTR_SF when the root hub is suspended. Try adding /* All ED unlinks should be finished, no need for SOF interrupts */ ohci_writel(ohci, OHCI_INTR_SF, &ohci->regs->intrdisable); into ohci_rh_suspend(), just before the update_done_list() call. If you add this then INTR_SF will not be enabled during S3 or S4 suspend, so the problem shouldn't occur. Does that work for you? >       In additon, when kernel include my patch, that it does't happen about > what you descriped that driver will not be able to finish unlinging URBs. > > Because above issue happen in S3/S4(Suspend to disk/Suspend to mem) test > procedure, if ed_rm_lis is no-NULL but my patch disable SoF interrupt. > > then when S3/S4 recovery to cpu idle state that usb resume will be called, > reume function has following logic, URB will continue to be processed. > >       static int ohci_rh_resume (struct ohci_hcd *ohci) > >      { > >         ... > >         242         if (ohci->ed_rm_list) >         243                 ohci_writel (ohci, OHCI_INTR_SF, > &ohci->regs->intrenable); > >        ... > >       } I'm worried that your patch may disable INTR_SF even when the controller has not gone into S3 or S4 suspend. Maybe this won't cause problems, but it's better to be safe and do the disable _only_ when a suspend occurs. Alan Stern