From patchwork Fri Mar 27 08:53:46 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tejas Joglekar X-Patchwork-Id: 11462025 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 192EF17EA for ; Fri, 27 Mar 2020 08:53:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D8ED420716 for ; Fri, 27 Mar 2020 08:53:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=synopsys.com header.i=@synopsys.com header.b="l7FEEOqA" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726383AbgC0Ixz (ORCPT ); Fri, 27 Mar 2020 04:53:55 -0400 Received: from smtprelay-out1.synopsys.com ([149.117.87.133]:41492 "EHLO smtprelay-out1.synopsys.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725946AbgC0Ixz (ORCPT ); Fri, 27 Mar 2020 04:53:55 -0400 Received: from mailhost.synopsys.com (mdc-mailhost1.synopsys.com [10.225.0.209]) (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 CBAEDC0F97; Fri, 27 Mar 2020 08:53:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=synopsys.com; s=mail; t=1585299234; bh=EJ8RV3plQh0+c4VOUvADF48eRGAn//pr/M5Ufp7Oeiw=; h=Date:In-Reply-To:References:From:Subject:To:Cc:From; b=l7FEEOqA5eRkonUkPGyyFVj/W9lfWVU7OtoNXCsMTN/vS/Zuk+DU2NsRuh7qK6sva sjgMKEP6Hu/V2rM5uFp4ORxNCZEzQKWLeD8Dkm+ogM7QDq4/r5yNYz1yvD2bMl6Uk5 Bv4jDvM0lbHijcLCKgir2KOHrxlgW4yZydOfJ3hzjdRGhZZ6MXJXIlHhlD270AOhg8 DbKQo7r7m23QEhLqdu2Th4kGSPVnk+4zPOzPyi188dZJK5x86HnfWAu26GlQ3SDltH dfWUGGDB2pvfaCC6wYqGUM9VsVFSErbaXLrPbTPNPqB4jND0JGXeL2rahQzRWymYWk 91/4+EcIb2efg== Received: from tejas-VirtualBox (joglekar-e7480.internal.synopsys.com [10.146.16.182]) (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 9E65FA005B; Fri, 27 Mar 2020 08:53:48 +0000 (UTC) Received: by tejas-VirtualBox (sSMTP sendmail emulation); Fri, 27 Mar 2020 14:23:46 +0530 Date: Fri, 27 Mar 2020 14:23:46 +0530 Message-Id: <5f7605b9f4cd2d6de4f0ef7d25be9a99d92c5aee.1585297723.git.joglekar@synopsys.com> In-Reply-To: References: From: Tejas Joglekar Subject: [RESENDING RFC PATCH 4/4] usb: xhci: Use temporary buffer to consolidate SG To: Tejas Joglekar , linux-usb@vger.kernel.org, Chunfeng Yun , Fredrik Noring , Mathias Nyman , Sebastian Andrzej Siewior , Raul E Rangel , Laurentiu Tudor , Marek Szyprowski Cc: John Youn Sender: linux-usb-owner@vger.kernel.org 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 --- Resending as 'umlaut' in email are not accepted by some servers. drivers/usb/core/hcd.c | 8 +++ drivers/usb/host/xhci-ring.c | 2 +- drivers/usb/host/xhci.c | 128 +++++++++++++++++++++++++++++++++++++++++++ drivers/usb/host/xhci.h | 4 ++ 4 files changed, 141 insertions(+), 1 deletion(-) diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c index aa45840d8273..fdd257a2b8a6 100644 --- a/drivers/usb/core/hcd.c +++ b/drivers/usb/core/hcd.c @@ -1459,6 +1459,14 @@ int usb_hcd_map_urb_for_dma(struct usb_hcd *hcd, struct urb *urb, return -EINVAL; } + /* + * If SG is consolidate into single buffer + * return early + */ + if ((urb->transfer_flags & + URB_DMA_MAP_SINGLE)) + return ret; + n = dma_map_sg( hcd->self.sysdev, urb->sg, diff --git a/drivers/usb/host/xhci-ring.c b/drivers/usb/host/xhci-ring.c index a78787bb5133..2fad9474912a 100644 --- a/drivers/usb/host/xhci-ring.c +++ b/drivers/usb/host/xhci-ring.c @@ -3291,7 +3291,7 @@ 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 fe38275363e0..94fddbd06179 100644 --- a/drivers/usb/host/xhci.c +++ b/drivers/usb/host/xhci.c @@ -1256,6 +1256,109 @@ 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 len; + unsigned int buf_len; + enum dma_data_direction dir; + struct xhci_hcd *xhci; + + xhci = hcd_to_xhci(hcd); + 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 (!temp) { + xhci_warn(xhci, "Failed to create temp buffer, HC may fail\n"); + return -ENOMEM; + } + + if (usb_urb_dir_out(urb)) { + len = sg_pcopy_to_buffer(urb->sg, urb->num_sgs, + temp, buf_len, 0); + if (len != buf_len) + xhci_warn(xhci, "Wrong temp buffer write length\n"); + } + + 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)) { + xhci_err(xhci, "dma mapping error\n"); + 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 buf_len; + unsigned int trb_size; + unsigned int max_pkt; + struct scatterlist *sg; + struct scatterlist *tail_sg; + + sg = urb->sg; + tail_sg = urb->sg; + buf_len = urb->transfer_buffer_length; + max_pkt = usb_endpoint_maxp(&urb->ep->desc); + + if (urb->dev->speed >= USB_SPEED_SUPER) + trb_size = TRB_CACHE_SIZE_SS; + else + trb_size = TRB_CACHE_SIZE_HS; + + 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 urb *urb) +{ + struct scatterlist *sg; + unsigned int len; + unsigned int buf_len; + + sg = urb->sg; + buf_len = urb->transfer_buffer_length; + + if (usb_urb_dir_in(urb)) { + len = sg_pcopy_from_buffer(urb->sg, urb->num_sgs, + urb->transfer_buffer, + buf_len, + 0); + if (len != buf_len) + dev_err(&urb->dev->dev, "Wrong length for unmap\n"); + } + + 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 @@ -1265,12 +1368,36 @@ 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_CONSOLIDATE_SG_LIST) { + if (xhci_urb_temp_buffer_required(hcd, urb)) + 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; + + usb_hcd_unmap_urb_for_dma(hcd, urb); + + if ((xhci->quirks & XHCI_CONSOLIDATE_SG_LIST) && unmap_temp_buf) + xhci_unmap_temp_buf(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 @@ -5315,6 +5442,7 @@ 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 a093eeaec70e..341d1dfbe689 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]; };