Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932864AbbFEN7J (ORCPT ); Fri, 5 Jun 2015 09:59:09 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:59561 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932796AbbFEN7D (ORCPT ); Fri, 5 Jun 2015 09:59:03 -0400 From: Luis Henriques To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Mathias Nyman , Greg Kroah-Hartman , Luis Henriques Subject: [PATCH 3.16.y-ckt 026/110] xhci: Solve full event ring by increasing TRBS_PER_SEGMENT to 256 Date: Fri, 5 Jun 2015 14:57:09 +0100 Message-Id: <1433512713-22984-27-git-send-email-luis.henriques@canonical.com> X-Mailer: git-send-email 2.1.4 In-Reply-To: <1433512713-22984-1-git-send-email-luis.henriques@canonical.com> References: <1433512713-22984-1-git-send-email-luis.henriques@canonical.com> X-Extended-Stable: 3.16 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2378 Lines: 57 3.16.7-ckt13 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Mathias Nyman commit 18cc2f4cbbaf825a4fedcf2d60fd388d291e0a38 upstream. Our event ring consists of only one segment, and we risk filling the event ring in case we get isoc transfers with short intervals such as webcams that fill a TD every microframe (125us) With 64 TRB segment size one usb camera could fill the event ring in 8ms. A setup with several cameras and other devices can fill up the event ring as it is shared between all devices. This has occurred when uvcvideo queues 5 * 32TD URBs which then get cancelled when the video mode changes. The cancelled URBs are returned in the xhci interrupt context and blocks the interrupt handler from handling the new events. A full event ring will block xhci from scheduling traffic and affect all devices conneted to the xhci, will see errors such as Missed Service Intervals for isoc devices, and and Split transaction errors for LS/FS interrupt devices. Increasing the TRB_PER_SEGMENT will also increase the default endpoint ring size, which is welcome as for most isoc transfer we had to dynamically expand the endpoint ring anyway to be able to queue the 5 * 32TDs uvcvideo queues. The default size used to be 64 TRBs per segment Signed-off-by: Mathias Nyman Signed-off-by: Greg Kroah-Hartman Signed-off-by: Luis Henriques --- drivers/usb/host/xhci.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h index d40a72b69f26..a70e45c7c440 100644 --- a/drivers/usb/host/xhci.h +++ b/drivers/usb/host/xhci.h @@ -1267,7 +1267,7 @@ union xhci_trb { * since the command ring is 64-byte aligned. * It must also be greater than 16. */ -#define TRBS_PER_SEGMENT 64 +#define TRBS_PER_SEGMENT 256 /* Allow two commands + a link TRB, along with any reserved command TRBs */ #define MAX_RSVD_CMD_TRBS (TRBS_PER_SEGMENT - 3) #define TRB_SEGMENT_SIZE (TRBS_PER_SEGMENT*16) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/