From patchwork Mon Nov 23 16:38:35 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tejas Joglekar X-Patchwork-Id: 11925713 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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 6C7B0C56202 for ; Mon, 23 Nov 2020 16:38:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1BDB52073C for ; Mon, 23 Nov 2020 16:38:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=synopsys.com header.i=@synopsys.com header.b="MjyPp+3b" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389895AbgKWQim (ORCPT ); Mon, 23 Nov 2020 11:38:42 -0500 Received: from smtprelay-out1.synopsys.com ([149.117.87.133]:34262 "EHLO smtprelay-out1.synopsys.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732512AbgKWQil (ORCPT ); Mon, 23 Nov 2020 11:38:41 -0500 Received: from mailhost.synopsys.com (mdc-mailhost2.synopsys.com [10.225.0.210]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)) (No client certificate requested) by smtprelay-out1.synopsys.com (Postfix) with ESMTPS id CE7DAC095F; Mon, 23 Nov 2020 16:38:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=synopsys.com; s=mail; t=1606149521; bh=LGRGuuln8596/KkNUATOt/0fU+wmK2r4bg4wqKYP6gc=; h=Date:In-Reply-To:References:From:Subject:To:Cc:From; b=MjyPp+3bfRwoR77S/vQyzalSgyVqXYGo6MK+LETNlIZwn9JAYwBN7HVXNu4XVtA8G jl92w/0Ew5bzIHB6kJ7F5MHvx0PIGfBHjuh905kx3aOme5MtafLt6g7cvfYatp4o4K TzFVE14F+aWIxxkrXrg6oN3oTd+IwdwnIQdsVhh4qNnL+WTKRlCDYl7w4StLqIg9W2 TfAaAZ65qV/D7pXWyibrpVC751WYf6way9JZ8MVgrxziRog8aUSCpdxXpFGQ+uDb2+ 8JKiVbzrP1zNM/mbm0aTus8twB5W+/CjtTxQyVExW/DFtWQ6k6X+LCXeCoHNZBuLaS MepiM07u4kdnQ== Received: from tejas-VirtualBox (joglekar-e7480.internal.synopsys.com [10.146.24.135]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mailhost.synopsys.com (Postfix) with ESMTPSA id B59B4A005D; Mon, 23 Nov 2020 16:38:37 +0000 (UTC) Received: by tejas-VirtualBox (sSMTP sendmail emulation); Mon, 23 Nov 2020 22:08:35 +0530 Date: Mon, 23 Nov 2020 22:08:35 +0530 Message-Id: <29b919fe9c3780d2cdcae59f7230786e4bbe1d0c.1606149078.git.joglekar@synopsys.com> In-Reply-To: References: X-SNPS-Relay: synopsys.com From: Tejas Joglekar Subject: [PATCH v6 2/3] usb: xhci: Use temporary buffer to consolidate SG To: Greg Kroah-Hartman , Tejas Joglekar , linux-usb@vger.kernel.org, Mathias Nyman Cc: John Youn Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org The Synopsys xHC has an internal TRB cache of size TRB_CACHE_SIZE for each endpoint. The default value for TRB_CACHE_SIZE is 16 for SS and 8 for HS. The controller loads and updates the TRB cache from the transfer ring in system memory whenever the driver issues a start transfer or update transfer command. For chained TRBs, the Synopsys xHC requires that the total amount of bytes for all TRBs loaded in the TRB cache be greater than or equal to 1 MPS. Or the chain ends within the TRB cache (with a last TRB). If this requirement is not met, the controller will not be able to send or receive a packet and it will hang causing a driver timeout and error. This can be a problem if a class driver queues SG requests with many small-buffer entries. The XHCI driver will create a chained TRB for each entry which may trigger this issue. This patch adds logic to the XHCI driver to detect and prevent this from happening. For every (TRB_CACHE_SIZE - 2), we check the total buffer size of the SG list and if the last window of (TRB_CACHE_SIZE - 2) SG list length and we don't make up at least 1 MPS, we create a temporary buffer to consolidate full SG list into the buffer. We check at (TRB_CACHE_SIZE - 2) window because it is possible that there would be a link and/or event data TRB that take up to 2 of the cache entries. We discovered this issue with devices on other platforms but have not yet come across any device that triggers this on Linux. But it could be a real problem now or in the future. All it takes is N number of small chained TRBs. And other instances of the Synopsys IP may have smaller values for the TRB_CACHE_SIZE which would exacerbate the problem. Signed-off-by: Tejas Joglekar --- drivers/usb/host/xhci-ring.c | 2 +- drivers/usb/host/xhci.c | 129 ++++++++++++++++++++++++++++++++++- drivers/usb/host/xhci.h | 4 ++ 3 files changed, 133 insertions(+), 2 deletions(-) diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index 167dae117f73..6d4dae5e5f21 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -3325,7 +3325,7 @@ int xhci_queue_bulk_tx(struct xhci_hcd *xhci, gfp_t mem_flags, full_len = urb->transfer_buffer_length; /* If we have scatter/gather list, we use it. */ - if (urb->num_sgs) { + if (urb->num_sgs && !(urb->transfer_flags & URB_DMA_MAP_SINGLE)) { num_sgs = urb->num_mapped_sgs; sg = urb->sg; addr = (u64) sg_dma_address(sg); diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c index d4a8d0efbbc4..5b0b5f1bb40d 100644 --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -1259,6 +1259,108 @@ EXPORT_SYMBOL_GPL(xhci_resume); /*-------------------------------------------------------------------------*/ +static int xhci_map_temp_buffer(struct usb_hcd *hcd, struct urb *urb) +{ + void *temp; + int ret = 0; + unsigned int buf_len; + enum dma_data_direction dir; + + dir = usb_urb_dir_in(urb) ? DMA_FROM_DEVICE : DMA_TO_DEVICE; + buf_len = urb->transfer_buffer_length; + + temp = kzalloc_node(buf_len, GFP_ATOMIC, + dev_to_node(hcd->self.sysdev)); + + if (usb_urb_dir_out(urb)) + sg_pcopy_to_buffer(urb->sg, urb->num_sgs, + temp, buf_len, 0); + + urb->transfer_buffer = temp; + urb->transfer_dma = dma_map_single(hcd->self.sysdev, + urb->transfer_buffer, + urb->transfer_buffer_length, + dir); + + if (dma_mapping_error(hcd->self.sysdev, + urb->transfer_dma)) { + ret = -EAGAIN; + kfree(temp); + } else { + urb->transfer_flags |= URB_DMA_MAP_SINGLE; + } + + return ret; +} + +static bool xhci_urb_temp_buffer_required(struct usb_hcd *hcd, + struct urb *urb) +{ + bool ret = false; + unsigned int i; + unsigned int len = 0; + unsigned int trb_size; + unsigned int max_pkt; + struct scatterlist *sg; + struct scatterlist *tail_sg; + + tail_sg = urb->sg; + max_pkt = usb_endpoint_maxp(&urb->ep->desc); + + if (!urb->num_sgs) + return ret; + + if (urb->dev->speed >= USB_SPEED_SUPER) + trb_size = TRB_CACHE_SIZE_SS; + else + trb_size = TRB_CACHE_SIZE_HS; + + if (urb->transfer_buffer_length != 0 && + !(urb->transfer_flags & URB_NO_TRANSFER_DMA_MAP)) { + for_each_sg(urb->sg, sg, urb->num_sgs, i) { + len = len + sg->length; + if (i > trb_size - 2) { + len = len - tail_sg->length; + if (len < max_pkt) { + ret = true; + break; + } + + tail_sg = sg_next(tail_sg); + } + } + } + return ret; +} + +static void xhci_unmap_temp_buf(struct usb_hcd *hcd, struct urb *urb) +{ + unsigned int len; + unsigned int buf_len; + enum dma_data_direction dir; + + dir = usb_urb_dir_in(urb) ? DMA_FROM_DEVICE : DMA_TO_DEVICE; + + buf_len = urb->transfer_buffer_length; + + if (IS_ENABLED(CONFIG_HAS_DMA) && + (urb->transfer_flags & URB_DMA_MAP_SINGLE)) + dma_unmap_single(hcd->self.sysdev, + urb->transfer_dma, + urb->transfer_buffer_length, + dir); + + if (usb_urb_dir_in(urb)) + len = sg_pcopy_from_buffer(urb->sg, urb->num_sgs, + urb->transfer_buffer, + buf_len, + 0); + + urb->transfer_flags &= ~URB_DMA_MAP_SINGLE; + kfree(urb->transfer_buffer); + urb->transfer_buffer = NULL; +} + /* * Bypass the DMA mapping if URB is suitable for Immediate Transfer (IDT), * we'll copy the actual data into the TRB address register. This is limited to @@ -1268,13 +1370,37 @@ EXPORT_SYMBOL_GPL(xhci_resume); static int xhci_map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb, gfp_t mem_flags) { + struct xhci_hcd *xhci; + + xhci = hcd_to_xhci(hcd); + if (xhci_urb_suitable_for_idt(urb)) return 0; + if (xhci->quirks & XHCI_SG_TRB_CACHE_SIZE_QUIRK) { + if (xhci_urb_temp_buffer_required(hcd, urb)) + return xhci_map_temp_buffer(hcd, urb); + } return usb_hcd_map_urb_for_dma(hcd, urb, mem_flags); } -/* +static void xhci_unmap_urb_for_dma(struct usb_hcd *hcd, struct urb *urb) +{ + struct xhci_hcd *xhci; + bool unmap_temp_buf = false; + + xhci = hcd_to_xhci(hcd); + + if (urb->num_sgs && (urb->transfer_flags & URB_DMA_MAP_SINGLE)) + unmap_temp_buf = true; + + if ((xhci->quirks & XHCI_SG_TRB_CACHE_SIZE_QUIRK) && unmap_temp_buf) + xhci_unmap_temp_buf(hcd, urb); + else + usb_hcd_unmap_urb_for_dma(hcd, urb); +} + +/** * xhci_get_endpoint_index - Used for passing endpoint bitmasks between the core and * HCDs. Find the index for an endpoint given its descriptor. Use the return * value to right shift 1 for the bitmask. @@ -5329,6 +5455,7 @@ static const struct hc_driver xhci_hc_driver = { * managing i/o requests and associated device resources */ .map_urb_for_dma = xhci_map_urb_for_dma, + .unmap_urb_for_dma = xhci_unmap_urb_for_dma, .urb_enqueue = xhci_urb_enqueue, .urb_dequeue = xhci_urb_dequeue, .alloc_dev = xhci_alloc_dev, diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h index d90c0d5df3b3..25e57bc9c3cc 100644 --- a/drivers/usb/host/xhci.h +++ b/drivers/usb/host/xhci.h @@ -1330,6 +1330,10 @@ enum xhci_setup_dev { #define TRB_SIA (1<<31) #define TRB_FRAME_ID(p) (((p) & 0x7ff) << 20) +/* TRB cache size for xHC with TRB cache */ +#define TRB_CACHE_SIZE_HS 8 +#define TRB_CACHE_SIZE_SS 16 + struct xhci_generic_trb { __le32 field[4]; };