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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 C9AF4C74A4B for ; Thu, 11 Jul 2019 07:37:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A6E3720838 for ; Thu, 11 Jul 2019 07:37:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728205AbfGKHhP (ORCPT ); Thu, 11 Jul 2019 03:37:15 -0400 Received: from mga09.intel.com ([134.134.136.24]:51049 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725963AbfGKHhP (ORCPT ); Thu, 11 Jul 2019 03:37:15 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 11 Jul 2019 00:37:14 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.63,476,1557212400"; d="scan'208";a="189420825" Received: from pipin.fi.intel.com (HELO pipin) ([10.237.72.175]) by fmsmga004.fm.intel.com with ESMTP; 11 Jul 2019 00:37:12 -0700 From: Felipe Balbi To: Rob Weber Cc: linux-usb@vger.kernel.org Subject: Re: dwc3 Disable Compliance Mode In-Reply-To: <20190710230110.GA3188@coops> References: <20190710230110.GA3188@coops> Date: Thu, 11 Jul 2019 10:37:11 +0300 Message-ID: <877e8phviw.fsf@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org Hi Rob, Rob Weber writes: > Hi Felipe, > > I hope you are doing well. My team and I are frequently experiencing an > issue with the dwc3 in our CherryTrail SoC where we encounter an LFPS > Polling timeout while our device is being enumerated. > > We configured the dwc3 as an ethernet gadget using configfs and the ecm > and RNDIS functions. The dwc3 transitions to U3 after configuration as > expected. Only once we connect our device to a USB host do we see the > link state transition to Polling. We are assuming LFPS Polling times > out because the link_state file in debugfs shows the link has > transitioned to compliance mode only after entering LFPS.Polling, and we > recently learned that compliance mode is triggered by a timeout during > LFPS.Polling. > > This issue is not 100% reproducible, but is occuring rather frequently > at the moment. We're unsure of the root cause of the issue as well. One > culprit might be the USB SuperSpeed Redriver we use in our design. > > We would like to disable compliance mode in the meantime to allow other > team members to continue developing and testing USB device mode features > while we dig into the root cause of the issue. Is there a proper way to > disable compliance mode entirely? That's not something that can be done, unfortunately. > If not, is there some mechanism we could implement to reset the > dwc3 when we enter compliance mode? I attempted some sort of mechanism > to reset the link state, but it does not seem to help the issue. I've > attached my patch and the trace events for my attempted workaround to > this email. My initial approach was to transition the link from > Compliance -> SS.Disabled -> Rx.Detect when we detect we've entered > compliance mode. The traces show that the dwc3 just enters LFPS.Polling > and subsequently enters compliance mode, despite the link being reset. I think you would have to go through the entire Power On Reset sequence, but that's likely to be flakey. > Do you have any ideas on how we might work around compliance mode in the > meantime? We have a few quirk flags that may help. snps,u2exit_lfps_quirk comes to mind, but I suggest trying a few of them and see if any helps. All flags are described in Documentation/devicetree/bindings/usb/dwc3.txt > /* -------------------------------------------------------------------------- */ > # tracer: nop > # > # entries-in-buffer/entries-written: 220/220 #P:4 > # > # _-----=> irqs-off > # / _----=> need-resched > # | / _---=> hardirq/softirq > # || / _--=> preempt-depth > # ||| / delay > # TASK-PID CPU# |||| TIMESTAMP FUNCTION > # | | | |||| | | > -0 [003] ..s1 178.444339: dwc3_core: Tick! Checking for compliance mode > > -0 [003] d.s2 178.444352: dwc3_core: Compliance Mode detected. Attempting recovery routine > irq/23-dwc3-1115 [002] d..1 178.445380: dwc3_event: event (00140301): Link Change [SS.Disabled] > irq/23-dwc3-1115 [002] d..1 178.445826: dwc3_event: event (00150301): Link Change [RX.Detect] > irq/23-dwc3-1115 [002] d..1 178.445832: dwc3_event: event (00170301): Link Change [Polling] > -0 [003] ..s1 180.492293: dwc3_core: Tick! Checking for compliance mode > > -0 [003] d.s2 180.492306: dwc3_core: Compliance Mode detected. Attempting recovery routine > > irq/23-dwc3-1115 [002] d..1 180.493333: dwc3_event: event (00140301): Link Change [SS.Disabled] > irq/23-dwc3-1115 [002] d..1 180.493636: dwc3_event: event (00150301): Link Change [RX.Detect] > irq/23-dwc3-1115 [002] d..1 180.493641: dwc3_event: event (00170301): Link Change [Polling] > -0 [003] ..s1 182.540350: dwc3_core: Tick! Checking for compliance mode > > -0 [003] d.s2 182.540362: dwc3_core: Compliance Mode detected. Attempting recovery routine > > irq/23-dwc3-1115 [002] d..1 182.541392: dwc3_event: event (00140301): Link Change [SS.Disabled] > irq/23-dwc3-1115 [002] d..1 182.541976: dwc3_event: event (00150301): Link Change [RX.Detect] > irq/23-dwc3-1115 [002] d..1 182.541982: dwc3_event: event (00170301): Link Change [Polling] > -0 [003] .Ns1 184.588211: dwc3_core: Tick! Checking for compliance mode > > -0 [003] dNs2 184.588232: dwc3_core: Compliance Mode detected. Attempting recovery routine Don't we get an interrupt for Compliance mode entry? cheers -- balbi