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 X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=no 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 1E701C432BE for ; Tue, 24 Aug 2021 12:32:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F15386127B for ; Tue, 24 Aug 2021 12:32:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237287AbhHXMdZ (ORCPT ); Tue, 24 Aug 2021 08:33:25 -0400 Received: from wtarreau.pck.nerim.net ([62.212.114.60]:39587 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230132AbhHXMdY (ORCPT ); Tue, 24 Aug 2021 08:33:24 -0400 Received: (from willy@localhost) by pcw.home.local (8.15.2/8.15.2/Submit) id 17OCWWJf025474; Tue, 24 Aug 2021 14:32:32 +0200 Date: Tue, 24 Aug 2021 14:32:32 +0200 From: Willy Tarreau To: Johan Hovold Cc: linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, Paul =?iso-8859-1?B?R3L232Vs?= , stable@vger.kernel.org Subject: Re: [PATCH] Revert "USB: serial: ch341: fix character loss at high transfer rates" Message-ID: <20210824123232.GA25435@1wt.eu> References: <20210824121926.19311-1-johan@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210824121926.19311-1-johan@kernel.org> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 24, 2021 at 02:19:26PM +0200, Johan Hovold wrote: > This reverts commit 3c18e9baee0ef97510dcda78c82285f52626764b. > > These devices do not appear to send a zero-length packet when the > transfer size is a multiple of the bulk-endpoint max-packet size. This > means that incoming data may not be processed by the driver until a > short packet is received or the receive buffer is full. > > Revert back to using endpoint-sized receive buffers to avoid stalled > reads. Sorry for this, I didn't notice any issue here (aside for the chip working where it used not to). I have no idea what these zero-length packets correspond to, nor why they're affected by the transfer size. Do you have any idea what I should look for ? Because without that patch, the device is unusable for me :-/ Thanks! Willy