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,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 BB0C8C433E6 for ; Tue, 26 Jan 2021 22:52:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7D4172065D for ; Tue, 26 Jan 2021 22:52:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730487AbhAZWu5 (ORCPT ); Tue, 26 Jan 2021 17:50:57 -0500 Received: from mga02.intel.com ([134.134.136.20]:27673 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727373AbhAZR3B (ORCPT ); Tue, 26 Jan 2021 12:29:01 -0500 IronPort-SDR: PsgF4g0dh3ASA5hTH6Lb4aJuTIhqTnGGMxgM5igZsX0NAIsHldEnBYRBuyGW66bD51wp4uok8o tksP9dkGtwLw== X-IronPort-AV: E=McAfee;i="6000,8403,9876"; a="167038608" X-IronPort-AV: E=Sophos;i="5.79,375,1602572400"; d="scan'208";a="167038608" Received: from fmsmga007.fm.intel.com ([10.253.24.52]) by orsmga101.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 26 Jan 2021 09:27:12 -0800 IronPort-SDR: d14Ju9eFHJNezkZ5EbK3yvzZ6ZtGnfwuOt1JDXHT27ScU5QB3PGec4E0B5ZLFasXoSIpoXcOGX 3FTm1OC4O9iA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.79,375,1602572400"; d="scan'208";a="350723610" Received: from mattu-haswell.fi.intel.com (HELO [10.237.72.170]) ([10.237.72.170]) by fmsmga007.fm.intel.com with ESMTP; 26 Jan 2021 09:27:11 -0800 Subject: Re: USB2 / USB3 compatibility problems: xhci_hcd 0000:00:06.0: WARN Wrong bounce buffer write length: 0 != 512 From: Mathias Nyman To: Andreas Hartmann , linux-usb@vger.kernel.org References: <3b4e35d2-9508-e0aa-eaf8-32e524ad81c4@01019freenet.de> <756e7b88-1142-4758-b8f7-a8eaf510b422@01019freenet.de> <7e953b15-925a-1512-4d15-c07fc03f9059@01019freenet.de> <8de6ecb9-4a39-5742-a358-d6965feffc79@linux.intel.com> 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: <8de6ecb9-4a39-5742-a358-d6965feffc79@linux.intel.com> 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 >> I'm not sure if it's important for you to know: The driver doesn't use struct scatterlist or num_mapped_sgs at all (if it's meant to be used by the sender at all). >> >> But it sets URB_NO_TRANSFER_DMA_MAP (for data transfer among others). >> >> Mlme packets are sent w/o bulk and w/o setting URB_NO_TRANSFER_DMA_MAP. All other packets are sent with URB_NO_TRANSFER_DMA_MAP turned on. >> > > Ok, thanks, I see what's going on here. > > Short recap of xhci alignment requirements. > 1. Data pointed to by a transfer request block (TRB) may not span 64k boundary > 2. If a transfer contains several TRBs, and spans over two TRB ringbuffer > segments, then the sum of the TRB data in the first segment must be a > multiple of max packets in size. > > Code assumes that if transfer is split into several blocks,(TRBs) and a block > in the middle of a transfer is smaller than max packet size, then it must be sg list. > > But this is not necessarily the case if data was already DMA mapped beforehand. > Data might start just before a 64k boundary, causing first TRB to be less than > packet size. > > I'll start implementing a fix for this. Got a first iteration ready, any change you could try it out? Thanks -Mathias 8<--- diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index 5677b81c0915..8df30618aaf1 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -699,11 +699,16 @@ static void xhci_unmap_td_bounce_buffer(struct xhci_hcd *xhci, dma_unmap_single(dev, seg->bounce_dma, ring->bounce_buf_len, DMA_FROM_DEVICE); /* for in tranfers we need to copy the data from bounce to sg */ - len = sg_pcopy_from_buffer(urb->sg, urb->num_sgs, seg->bounce_buf, - seg->bounce_len, seg->bounce_offs); - if (len != seg->bounce_len) - xhci_warn(xhci, "WARN Wrong bounce buffer read length: %zu != %d\n", - len, seg->bounce_len); + if (urb->num_sgs) { + len = sg_pcopy_from_buffer(urb->sg, urb->num_sgs, seg->bounce_buf, + seg->bounce_len, seg->bounce_offs); + if (len != seg->bounce_len) + xhci_warn(xhci, "WARN Wrong bounce buffer read length: %zu != %d\n", + len, seg->bounce_len); + } else { + memcpy(urb->transfer_buffer + seg->bounce_offs, seg->bounce_buf, + seg->bounce_len); + } seg->bounce_len = 0; seg->bounce_offs = 0; } @@ -3275,12 +3280,16 @@ static int xhci_align_td(struct xhci_hcd *xhci, struct urb *urb, u32 enqd_len, /* create a max max_pkt sized bounce buffer pointed to by last trb */ if (usb_urb_dir_out(urb)) { - len = sg_pcopy_to_buffer(urb->sg, urb->num_sgs, - seg->bounce_buf, new_buff_len, enqd_len); - if (len != new_buff_len) - xhci_warn(xhci, - "WARN Wrong bounce buffer write length: %zu != %d\n", - len, new_buff_len); + if (urb->num_sgs) { + len = sg_pcopy_to_buffer(urb->sg, urb->num_sgs, + seg->bounce_buf, new_buff_len, enqd_len); + if (len != new_buff_len) + xhci_warn(xhci, "WARN Wrong bounce buffer write length: %zu != %d\n", + len, new_buff_len); + } else { + memcpy(seg->bounce_buf, urb->transfer_buffer + enqd_len, new_buff_len); + } + seg->bounce_dma = dma_map_single(dev, seg->bounce_buf, max_pkt, DMA_TO_DEVICE); } else {