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 22943C433F5 for ; Tue, 12 Oct 2021 14:38:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0397960EB4 for ; Tue, 12 Oct 2021 14:38:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237324AbhJLOke (ORCPT ); Tue, 12 Oct 2021 10:40:34 -0400 Received: from netrider.rowland.org ([192.131.102.5]:56923 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S237347AbhJLOkc (ORCPT ); Tue, 12 Oct 2021 10:40:32 -0400 Received: (qmail 857016 invoked by uid 1000); 12 Oct 2021 10:38:30 -0400 Date: Tue, 12 Oct 2021 10:38:30 -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 v5] usb: ohci: disable start-of-frame interrupt in ohci_rh_suspend Message-ID: <20211012143830.GA855318@rowland.harvard.edu> References: <1634027450-3358-1-git-send-email-zhuyinbo@loongson.cn> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 12, 2021 at 08:11:45PM +0800, zhuyinbo wrote: > > 在 2021/10/12 下午4:30, Yinbo Zhu 写道: > > 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 and S4 (suspend to memory/suspend > > to disk) press test procedure, it may happen that the start-of- > > frame was launched in UsbSuspend status and cause ohci works failed > > that the phenomenon was hc will allways reproduce the SoF interrupt > > and consider that hc doesn't deal with the ed/td/done list in non- > > UsbOperational, and this patch was to disable SoF interrupt in ohci > > _rh_suspend so that it can fix ohci SoF abnormally interrupt issue. > > > > Signed-off-by: Yinbo Zhu > > --- > > Change in v5: > > Move the key code change into ohci_rh_suspend. > > Rework the commit log information. > > > > > > drivers/usb/host/ohci-hub.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/drivers/usb/host/ohci-hub.c b/drivers/usb/host/ohci-hub.c > > index f474f2f..80a0094 100644 > > --- a/drivers/usb/host/ohci-hub.c > > +++ b/drivers/usb/host/ohci-hub.c > > @@ -88,6 +88,8 @@ static int ohci_rh_suspend (struct ohci_hcd *ohci, int autostop) > > msleep (8); > > spin_lock_irq (&ohci->lock); > > } > > + /* All ED unlinks should be finished, no need for SOF interrupts */ > > + ohci_writel(ohci, OHCI_INTR_SF, &ohci->regs->intrdisable); > > update_done_list(ohci); > > ohci_work(ohci); > > Hi Alan Stern, > >     I consider that autostop sometimes was '1' then and HC doesn't  stop > deal with the ed/td/done list , then ohci_wok will called start_ed_unlink > and > >     start_ed_unlink will enable INTR_SF as follows, so I think add above two > line code after ohci_work it is more appropriate, Do you think so? > >       static void start_ed_unlink (struct ohci_hcd *ohci, struct ed *ed) >        { > >              ... > >              494         /* enable SOF interrupt */ >              495         ohci_writel (ohci, OHCI_INTR_SF, > &ohci->regs->intrstatus); >              496         ohci_writel (ohci, OHCI_INTR_SF, > &ohci->regs->intrenable); > >               ... > >         } Yes, that's a good point. Go ahead and make this change. And be sure to put a blank line before the new comment line. I also think the patch description should be rewritten. It talks about things that are not relevant to the patch. For example, you don't _know_ that your host controller is sending SOF packets in the non-UsbOperational state; you only know that it is generating interrupts with the INTR_SF flag set. So you should change the description to something like this: While going into S3 or S4 suspend, an OHCI host controller can generate interrupt requests if the INTR_SF enable flag is set. The interrupt handler routine isn't prepared for this and it doesn't turn off the flag, causing an interrupt storm. To fix this problem, make ohci_rh_suspend() always disable INTR_SF interrupts after processing the done list and the ED unlinks but before the controller goes into the suspended (non-UsbOperational) state. There's no reason to leave the flag enabled, since a suspended controller doesn't generate Start-of-Frame packets. Alan Stern