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=-6.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 7DF81C433E0 for ; Tue, 23 Feb 2021 16:14:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 414B464E3F for ; Tue, 23 Feb 2021 16:14:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233546AbhBWQOl (ORCPT ); Tue, 23 Feb 2021 11:14:41 -0500 Received: from mail.kernel.org ([198.145.29.99]:37772 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233514AbhBWQOi (ORCPT ); Tue, 23 Feb 2021 11:14:38 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9F96A64E3F; Tue, 23 Feb 2021 16:13:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1614096835; bh=X7jJSpYpIlmkfxxrNGHU1k1r6tFSjeHHP8+BtWzUXaY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=feJp0gYxZDo2vBkRN0r6Dqj9Dk9nlfO27Ma13juDpnrsuPO4pqtbmuCRviXqkEez+ QxDEQ7ttSJABwoFHEOiv5XNnwtFIHrvVfFPKBGmQgNo8j7jUe85SuiFpszowetbrd7 qgQtassVtDNXY0GQOHQOXH1SrdDqDIA8B4N3VtbJlgGiNWC2MDWufxuhbwVxvMM1B5 jLfYKMOLp27EByAOvFb5AvNspmQTbUf8FSfv7/N7ryKzDLLR7MeIvKvjRRq3nb4TEX tiDry/j3pUfbFf/rJL29mNTXCGmZoDGFOCtk7WP5Nl+OQIPswTtEXyOtAEBOo6J5kY 4NjYOXugbnOIw== Received: from johan by xi.lan with local (Exim 4.93.0.4) (envelope-from ) id 1lEaKA-0004gN-DC; Tue, 23 Feb 2021 17:14:11 +0100 Date: Tue, 23 Feb 2021 17:14:10 +0100 From: Johan Hovold To: "Michael G. Katzmann" Cc: charles-yeh@prolific.com.tw, linux-serial@vger.kernel.org, linux-usb@vger.kernel.org, Charles Yeh , Joe Abbott Subject: Re: non-standard baud rates with Prolific 2303 USB-serial Message-ID: References: <0f9caf26-af58-13a9-9947-47bb646f505e@IEEE.org> <780b9aa6-890d-47fd-d6b2-cd9a39f7634a@IEEE.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On Tue, Feb 23, 2021 at 10:57:09AM -0500, Michael G. Katzmann wrote: > On 2/23/21 10:43 AM, Johan Hovold wrote: > > On Tue, Feb 23, 2021 at 09:58:47AM -0500, Michael G. Katzmann wrote: > >> Is it that we are presuming that what Prolific is telling us is true > >> and only Joe and I are actually measuring the data rate?  (i.e. why > >> does the Prolific Windows driver set the values as Joe found ???) > > I'm starting to think they've added some alternate baud rate encoding in > > order to make life harder for the people pushing (or unknowingly buying) > > counterfeit devices. > > > > As you say, why else would the Windows driver support this encoding? > > I find that  'Halon;'s razor' is helpful in these situations...  I > can't think that messing with people who use old teleprinters would be > useful in protecting one's products 8-) Heh, guess you're right. > If Joe has some wireshark traces we can see if there are any vendor > specific USB packets. If not I can try it (I'd be starting from > scratch as I've only use wireshark on Linux). > > I presume you can't see any differentiators in the normal USB > identifiers that we can use.  I only have an HXD (and a GC) here. The HXD has bcdUSB as 1.10 unlike your TA with 2.00, but not sure that helps. > If someone has a device that works under the existing driver, it would > be helpful to see if the modified scheme also works on those devices? I tried with both of mine when Joe reported this and neither works with the alternate scheme (and the GC turned out not to even support divisor encoding). Johan