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 4AAA1C433F5 for ; Tue, 15 Feb 2022 10:49:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236692AbiBOKtl (ORCPT ); Tue, 15 Feb 2022 05:49:41 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:59294 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236021AbiBOKti (ORCPT ); Tue, 15 Feb 2022 05:49:38 -0500 Received: from alexa-out-sd-01.qualcomm.com (alexa-out-sd-01.qualcomm.com [199.106.114.38]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4898ABB56D; Tue, 15 Feb 2022 02:49:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1644922168; x=1676458168; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=d8wfwR/uCveJ2Q94/EFl7igRbByuFJMssLIeSVMsf1s=; b=Xd9HPtVv6QpbV4HWuI4bTcqWrv1KyCDoj4d/3QeAXiWQvsjy5VI6iZU6 bgrDjFeM9tiZiS5TrDuwdnUSvVuTMcemvX3sTYwjArx5wbjn2uarhk5A6 KxHEKI6vJ+hWMXHtqFjooL6GSjSstm0pVHFqWREQTtBq2wKq6YUecnonh k=; Received: from unknown (HELO ironmsg-SD-alpha.qualcomm.com) ([10.53.140.30]) by alexa-out-sd-01.qualcomm.com with ESMTP; 15 Feb 2022 02:49:27 -0800 X-QCInternal: smtphost Received: from nasanex01c.na.qualcomm.com ([10.47.97.222]) by ironmsg-SD-alpha.qualcomm.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Feb 2022 02:49:27 -0800 Received: from nalasex01a.na.qualcomm.com (10.47.209.196) by nasanex01c.na.qualcomm.com (10.47.97.222) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.15; Tue, 15 Feb 2022 02:49:27 -0800 Received: from hu-pkondeti-hyd.qualcomm.com (10.80.80.8) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.922.19; Tue, 15 Feb 2022 02:49:24 -0800 Date: Tue, 15 Feb 2022 16:19:20 +0530 From: Pavan Kondeti To: Mathias Nyman CC: Pavan Kondeti , Greg Kroah-Hartman , Mathias Nyman , , , , Jung Daehwan Subject: Re: [PATCH v2] xhci: reduce xhci_handshake timeout in xhci_reset Message-ID: <20220215104920.GE31021@hu-pkondeti-hyd.qualcomm.com> References: <1644836663-29220-1-git-send-email-quic_pkondeti@quicinc.com> <1644841216-1468-1-git-send-email-quic_pkondeti@quicinc.com> <20220214135310.GC31021@hu-pkondeti-hyd.qualcomm.com> <1b9e7641-2ae9-0f81-2ad9-18340d5e148f@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <1b9e7641-2ae9-0f81-2ad9-18340d5e148f@linux.intel.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01b.na.qualcomm.com (10.46.141.250) To nalasex01a.na.qualcomm.com (10.47.209.196) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Mathias, On Tue, Feb 15, 2022 at 12:16:12PM +0200, Mathias Nyman wrote: > On 14.2.2022 15.53, Pavan Kondeti wrote: > > Hi Mathias, > > > > On Mon, Feb 14, 2022 at 02:51:54PM +0200, Mathias Nyman wrote: > >> On 14.2.2022 14.20, Pavankumar Kondeti wrote: > >>> From: Daehwan Jung > >>> > >>> xhci_reset() is called with interrupts disabled. Waiting 10 seconds for > >>> controller reset and controller ready operations can be fatal to the > >>> system when controller is timed out. Reduce the timeout to 1 second > >>> and print a error message when the time out happens. > >>> > >>> Fixes: 22ceac191211 ("xhci: Increase reset timeout for Renesas 720201 host.") > >> > >> > >> The commit 22ceac191211 ("xhci: Increase reset timeout for Renesas 720201 host.") > >> intentionally increased the timeout to 10 seconds as that host might take 9 > >> seconds to complete reset. This was done almost 10 years ago so I don't know > >> if it really is an issue anymore. > >> > >> Anyways, your patch might break Renesas 72021 instead of fixing it. > > > > Unfortunately, yes :-( . We have this reduced timeout patch in our previous > > commercialized products so thought this would be a good time to fix this > > once for all. Since this patch has been 10 years long, not sure if any other > > controllers also need 10 sec timeout. It would probably better > > > >> > >> I agree that busylooping up to 10 seconds with interrupts disabled doesn't make sense. > >> > >> Lets see if there is another solution for your case. > >> > >> - Does a "guard interval" after writing the reset help? > >> For example Intel xHCI needs 1ms before touching xHC after writing the reset bit > > > > I will ask this question to our hardware team. Setting that one quirk from > > DWC3 host might require other changes like this [1]. > >> > >> - Is it the CNR bit or the RESET bit that fails? could be just stuck CNR bit? > > > > The RESET bit never gets cleared from USBCMD register. > > > >> > >> - we only disable local interrupts when xhci_reset() is called from xhci_stop(), > >> and sometimes from xhci_shutdown() and xhci_resume() if some conditions are met. > >> Have you identified which one is the problematic case? > > > > The crash reports I have seen are pointing to > > > > usb_remove_hcd()->xhci_stop()->xhci_reset() > > Ok, so xhci_stop() and xhci_shutdown() both may call xhci_reset() with interrupts > disabled and spinlock held. In both these cases we're not that interested in the > outcome of xhci_reset(). > > But during probe we call xhci_reset() with interrupts enabled without spinlock, > and here we really care about it succeeding. > I'm also guessing reset could take a longer time during probe due to possible recent > BIOS handover, or firmware loading etc. > > So how about passing a timeout value to xhci_reset()? > Give it 10 seconds during probe, and 250ms in the other cases. > Thanks for this suggestion. This sounds better compared to the quirks approach. xhci_resume() also seems to be calling xhci_reset() in the hibernation path, I believe we should treat this like probe()/startup case and give larger timeout. Thanks, Pavan