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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D80C1C4332F for ; Sun, 16 Oct 2022 11:47:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229579AbiJPLrX (ORCPT ); Sun, 16 Oct 2022 07:47:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50522 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229531AbiJPLrV (ORCPT ); Sun, 16 Oct 2022 07:47:21 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 97224357EF for ; Sun, 16 Oct 2022 04:47:20 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 20C3660A4B for ; Sun, 16 Oct 2022 11:47:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2ACB7C433C1; Sun, 16 Oct 2022 11:47:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1665920839; bh=939rYgjXfEkUXa4BlOnOuDMNGiTFLQepD5vWv0ahUMc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=2p3em1AMm8AWm4uG9Qj2UeQPL27JiaNHE0osu8v+/1jrD1W/5ISQNXPT/RgH/C2S8 hEcXmPL4rRm/DxcF93tSImn4ChWJkaRvvIgXEKg/TmqpRZMlVQQZwtEpJxW9pJSq9X 2McvFFHtzTpcRT8VhqE9mQspxqEhjMd3IeLaZ8/o= Date: Sun, 16 Oct 2022 13:48:05 +0200 From: Greg KH To: Chun-Chao Yen Cc: pabeni@redhat.com, davem@davemloft.net, linux-usb@vger.kernel.org Subject: Re: [PATCH 1/3 (RESENT)] net: usb: ax88179_178a: Enable FLAG_MULTI_PACKET to improve tx stability Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Sun, Oct 16, 2022 at 07:36:25PM +0800, Chun-Chao Yen wrote: > Problem Description: > The current way of handling the boundary case in tx, i.e. adding one-byte > padding when the size of an outbound packet is a multiple of the maximum > frame size used for USB bulk transfer, does not work with the hardware. > This can be shown by running a loading test via iperf with this hardware as > the sender; one can then tune the iperf parameters on the sender side (e.g. > "-M 510" in my testing environment) so that sent packets frequently hit the > boundary condition, and observe a significant drop in the transmission > rate. In the worst case (often after a long run), the hardware can stop > functioning (can not send or receive packets anymore, albeit the > corresponding network interface is still reported present by ifconfig). > > It is also believed that this problem is highly relevant to this bug [1]. > > Solution: > Enable FLAG_MULTI_PACKET and modify both ax88179_rx_fixup() and > ax88179_tx_fixup() accordingly. > > Rationale: > When FLAG_MULTI_PACKET is enabled (and FLAG_SEND_ZLP is off, which is the > case for this driver), usbnet will skip padding, and trust that each > sk_buff returned from the mini-driver's tx_fixup function has been taken > care of to cater for the requirement of its target hardware. That > mechanism allows this mini-driver to send, even when the boundary condition > is detected, "untampered" packets (no padding, no extra flags, as if in the > normal case) that the hardware accepts, and therefore resolves this > problem. > > Note that rather than being viewed as a workaround, enabling > FLAG_MULTI_PACKET is intended to better match the overall behaviour of the > hardware, as it also echos well the rx procedure conducting multiple-packet > extraction from a single sk_buff in ax88179_rx_fixup(). > > Verification: > Only tested with this device: > 0b95:1790 ASIX Electronics Corp. AX88179 Gigabit Ethernet > > References: > [1] https://bugzilla.kernel.org/show_bug.cgi?id=212731 > > Signed-off-by: Chun-Chao Yen > --- > drivers/net/usb/ax88179_178a.c | 62 ++++++++++++++-------------------- > 1 file changed, 26 insertions(+), 36 deletions(-) Why is this a RESEND? Always put below the --- what is happening, what is different from the first version you sent? And why is this not threaded with the 2/3 and 3/3 patches? thanks, greg k-h