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=-10.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 8F176C433ED for ; Wed, 21 Apr 2021 07:26:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4E2C9613D7 for ; Wed, 21 Apr 2021 07:26:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231463AbhDUH1G (ORCPT ); Wed, 21 Apr 2021 03:27:06 -0400 Received: from mga18.intel.com ([134.134.136.126]:34265 "EHLO mga18.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230098AbhDUH1E (ORCPT ); Wed, 21 Apr 2021 03:27:04 -0400 IronPort-SDR: 8KzUhe53Ofq6mknneK0IH2Kj1DID8Pc5XOA+qGR9VUKlLOeogpzpwpNB1Lm6Pp+dWJerWdes1r lIcj2jdniNXA== X-IronPort-AV: E=McAfee;i="6200,9189,9960"; a="183143199" X-IronPort-AV: E=Sophos;i="5.82,238,1613462400"; d="scan'208";a="183143199" Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga106.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Apr 2021 00:26:24 -0700 IronPort-SDR: h0PvQQ+yuCZdr/tVpKsHl/RThViX7D/w9tz4uvwXLDirnNr3aPZyFW1mmvH0v0rnc5vCw4mTlS XB3K6f50KrQw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.82,238,1613462400"; d="scan'208";a="617256828" Received: from mattu-haswell.fi.intel.com (HELO [10.237.72.170]) ([10.237.72.170]) by fmsmga005.fm.intel.com with ESMTP; 21 Apr 2021 00:26:19 -0700 Subject: Re: [PATCH] [RFC] xhci: Add Link TRB sync quirk for ASM3142 To: Ole Salscheider , Mathias Nyman , linux-usb@vger.kernel.org References: <20210416093729.41865-1-ole@salscheider.org> <9bf0060c-3427-a261-531c-c075054ae094@linux.intel.com> <5c92dd8c-c8b0-40b5-addb-2df360673462@salscheider.org> From: Mathias Nyman Autocrypt: addr=mathias.nyman@linux.intel.com; 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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 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On 19.4.2021 22.05, Ole Salscheider wrote: > Hi Mathias, ... >> tracing shows the content of the TRB while it's written, before writing the cycle bit. >> Could be worth dumping transfer ring after issue is seen and check TRB still looks valid: >> cat /sys/kernel/debug/usb/xhci//devices//ep/trbs >> you need to figure out which controller, device and endpoint number for this. > > I think this is the output for the correct device and endpoint: > > https://stuff.salscheider.org/trbs Thanks, the TRB was already turned No-op by the cancel code by then, but it doesn't matter, your trace below indicates the TRB is fine. > >> How about your delayed link TRB cycle write patch? did it help trigger an event for the last transfer >> TRB, or did it just help as controller couldn't go past the link TRB and was less out of sync with >> the driver? > > > You can find a trace of recording a few seconds of video with my patch here: > > https://stuff.salscheider.org/trace_with_patch > > As far as I can tell from it, the patch helps to trigger an event for all transfer TRBs. I also tried to record around 30 min of video with it and it did not encounter a problem while recording. > > I however cannot start a new recording after stopping the first. And sometimes I observe hangs of the computer some time after stopping the recording. That might be some unwanted side-effect of my patch... > Yes, It shows transfer events for the TRBs before the link TRB. This workaround is however a can of worms as many TD's consist of several TRBs, and they only trigger events for the last TRB. How about a different approach? If the issue is only with transfers starting on the last TRB before the link TRB, we could turn that TRB to a no-op. Does something like the code below help? diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index 6cdea0d00d19..0ffda8127640 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -3181,6 +3181,12 @@ static int prepare_ring(struct xhci_hcd *xhci, struct xhci_ring *ep_ring, } } + if (ep_ring != xhci->cmd_ring && + !trb_is_link(ep_ring->enqueue) && + trb_is_link(ep_ring->enqueue + 1)) + queue_trb(xhci, ep_ring, 0, 0, 0, 0, + TRB_TYPE(TRB_TR_NOOP) | ep_ring->cycle_state); + while (trb_is_link(ep_ring->enqueue)) { /* If we're not dealing with 0.95 hardware or isoc rings * on AMD 0.96 host, clear the chain bit. -Mathias