From patchwork Fri Mar 19 07:37:21 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hayes Wang X-Patchwork-Id: 405226 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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 66F7BC433E0 for ; Fri, 19 Mar 2021 07:39:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1BB3764F68 for ; Fri, 19 Mar 2021 07:39:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234198AbhCSHjD (ORCPT ); Fri, 19 Mar 2021 03:39:03 -0400 Received: from rtits2.realtek.com ([211.75.126.72]:54443 "EHLO rtits2.realtek.com.tw" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234158AbhCSHjB (ORCPT ); Fri, 19 Mar 2021 03:39:01 -0400 Authenticated-By: X-SpamFilter-By: ArmorX SpamTrap 5.73 with qID 12J7cvltF005050, This message is accepted by code: ctloc85258 Received: from mail.realtek.com (rtexmbs04.realtek.com.tw[172.21.6.97]) by rtits2.realtek.com.tw (8.15.2/2.70/5.88) with ESMTPS id 12J7cvltF005050 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT); Fri, 19 Mar 2021 15:38:57 +0800 Received: from fc32.localdomain (172.21.177.102) by RTEXMBS04.realtek.com.tw (172.21.6.97) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Fri, 19 Mar 2021 15:38:57 +0800 From: Hayes Wang To: CC: , , , Hayes Wang , Robert Davies Subject: [PATCH net] r8152: limit the RX buffer size of RTL8153A for USB 2.0 Date: Fri, 19 Mar 2021 15:37:21 +0800 Message-ID: <1394712342-15778-349-Taiwan-albertk@realtek.com> X-Mailer: Microsoft Office Outlook 11 MIME-Version: 1.0 X-Originating-IP: [172.21.177.102] X-ClientProxiedBy: RTEXMBS01.realtek.com.tw (172.21.6.94) To RTEXMBS04.realtek.com.tw (172.21.6.97) Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org Message-ID: <20210319073721.ZMm7VgofwBbrO92SfDnv-CJ85-YCvWz7loFIGe_OAiw@z> If the USB host controller is EHCI, the throughput is reduced from 300Mb/s to 60Mb/s, when the rx buffer size is modified from 16K to 32K. According to the EHCI spec, the maximum size of the qTD is 20K. Therefore, when the driver uses more than 20K buffer, the latency time of EHCI would be increased. And, it let the RTL8153A get worse throughput. However, the driver uses alloc_pages() for rx buffer, so I limit the rx buffer to 16K rather than 20K. BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=205923 Fixes: ec5791c202ac ("r8152: separate the rx buffer size") Reported-by: Robert Davies Signed-off-by: Hayes Wang --- drivers/net/usb/r8152.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c index 90f1c0200042..20fb5638ac65 100644 --- a/drivers/net/usb/r8152.c +++ b/drivers/net/usb/r8152.c @@ -6553,7 +6553,10 @@ static int rtl_ops_init(struct r8152 *tp) ops->in_nway = rtl8153_in_nway; ops->hw_phy_cfg = r8153_hw_phy_cfg; ops->autosuspend_en = rtl8153_runtime_enable; - tp->rx_buf_sz = 32 * 1024; + if (tp->udev->speed < USB_SPEED_SUPER) + tp->rx_buf_sz = 16 * 1024; + else + tp->rx_buf_sz = 32 * 1024; tp->eee_en = true; tp->eee_adv = MDIO_EEE_1000T | MDIO_EEE_100TX; break;