From patchwork Sun Nov 15 21:39:08 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Clemens Ladisch X-Patchwork-Id: 7620121 Return-Path: X-Original-To: patchwork-alsa-devel@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id DBC47BF90C for ; Sun, 15 Nov 2015 21:41:01 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id F3AA620272 for ; Sun, 15 Nov 2015 21:41:00 +0000 (UTC) Received: from alsa0.perex.cz (alsa0.perex.cz [77.48.224.243]) by mail.kernel.org (Postfix) with ESMTP id 931172024F for ; Sun, 15 Nov 2015 21:40:59 +0000 (UTC) Received: by alsa0.perex.cz (Postfix, from userid 1000) id B681A26147A; Sun, 15 Nov 2015 22:40:58 +0100 (CET) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_LOW, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 Received: from alsa0.perex.cz (localhost [127.0.0.1]) by alsa0.perex.cz (Postfix) with ESMTP id 9036D261A53; Sun, 15 Nov 2015 22:40:31 +0100 (CET) X-Original-To: alsa-devel@alsa-project.org Delivered-To: alsa-devel@alsa-project.org Received: by alsa0.perex.cz (Postfix, from userid 1000) id B66E2261A64; Sun, 15 Nov 2015 22:40:30 +0100 (CET) Received: from dehamd003.servertools24.de (dehamd003.servertools24.de [31.47.254.18]) by alsa0.perex.cz (Postfix) with ESMTP id 2C9DB2606FE for ; Sun, 15 Nov 2015 22:40:05 +0100 (CET) Received: from [192.168.42.201] (tmo-096-43.customers.d1-online.com [80.187.96.43]) by dehamd003.servertools24.de (Postfix) with ESMTPSA id 74BC4F520024; Sun, 15 Nov 2015 22:40:04 +0100 (CET) To: Takashi Iwai References: <5648FAED.8020300@ladisch.de> From: Clemens Ladisch Message-ID: <5648FB7C.9060500@ladisch.de> Date: Sun, 15 Nov 2015 22:39:08 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <5648FAED.8020300@ladisch.de> X-PPP-Message-ID: <20151115214004.346859.61350@dehamd003.servertools24.de> X-PPP-Vhost: ladisch.de Cc: alsa-devel@alsa-project.org Subject: [alsa-devel] [PATCH 3/3] ALSA: usb-audio: work around CH345 input SysEx corruption X-BeenThere: alsa-devel@alsa-project.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "Alsa-devel mailing list for ALSA developers - http://www.alsa-project.org" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: alsa-devel-bounces@alsa-project.org Sender: alsa-devel-bounces@alsa-project.org X-Virus-Scanned: ClamAV using ClamSMTP One of the many faults of the QinHeng CH345 USB MIDI interface chip is that it does not handle received SysEx messages correctly -- every second event packet has a wrong code index number, which is the one from the last seen message, instead of 4. For example, the two messages "FE F0 01 02 03 04 05 06 07 08 09 0A 0B 0C 0D 0E F7" result in the following event packets: correct: CH345: 0F FE 00 00 0F FE 00 00 04 F0 01 02 04 F0 01 02 04 03 04 05 0F 03 04 05 04 06 07 08 04 06 07 08 04 09 0A 0B 0F 09 0A 0B 04 0C 0D 0E 04 0C 0D 0E 05 F7 00 00 05 F7 00 00 A class-compliant driver must interpret an event packet with CIN 15 as having a single data byte, so the other two bytes would be ignored. The message received by the host would then be missing two bytes out of six; in this example, "F0 01 02 03 06 07 08 09 0C 0D 0E F7". These corrupted SysEx event packages contain only data bytes, while the CH345 uses event packets with a correct CIN value only for messages with a status byte, so it is possible to distinguish between these two cases by checking for the presence of this status byte. (Other bugs in the CH345's input handling, such as the corruption resulting from running status, cannot be worked around.) Signed-off-by: Clemens Ladisch Cc: stable@vger.kernel.org --- sound/usb/midi.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/sound/usb/midi.c b/sound/usb/midi.c index 010094a..5b4c58c 100644 --- a/sound/usb/midi.c +++ b/sound/usb/midi.c @@ -174,6 +174,8 @@ struct snd_usb_midi_in_endpoint { u8 running_status_length; } ports[0x10]; u8 seen_f5; + bool in_sysex; + u8 last_cin; u8 error_resubmit; int current_port; }; @@ -468,6 +470,39 @@ static void snd_usbmidi_maudio_broken_running_status_input( } /* + * QinHeng CH345 is buggy: every second packet inside a SysEx has not CIN 4 + * but the previously seen CIN, but still with three data bytes. + */ +static void ch345_broken_sysex_input(struct snd_usb_midi_in_endpoint *ep, + uint8_t *buffer, int buffer_length) +{ + unsigned int i, cin, length; + + for (i = 0; i + 3 < buffer_length; i += 4) { + if (buffer[i] == 0 && i > 0) + break; + cin = buffer[i] & 0x0f; + if (ep->in_sysex && + cin == ep->last_cin && + (buffer[i + 1 + (cin == 0x6)] & 0x80) == 0) + cin = 0x4; +#if 0 + if (buffer[i + 1] == 0x90) { + /* + * Either a corrupted running status or a real note-on + * message; impossible to detect reliably. + */ + } +#endif + length = snd_usbmidi_cin_length[cin]; + snd_usbmidi_input_data(ep, 0, &buffer[i + 1], length); + ep->in_sysex = cin == 0x4; + if (!ep->in_sysex) + ep->last_cin = cin; + } +} + +/* * CME protocol: like the standard protocol, but SysEx commands are sent as a * single USB packet preceded by a 0x0F byte. */ @@ -660,6 +695,12 @@ static struct usb_protocol_ops snd_usbmidi_cme_ops = { .output_packet = snd_usbmidi_output_standard_packet, }; +static struct usb_protocol_ops snd_usbmidi_ch345_broken_sysex_ops = { + .input = ch345_broken_sysex_input, + .output = snd_usbmidi_standard_output, + .output_packet = snd_usbmidi_output_standard_packet, +}; + /* * AKAI MPD16 protocol: * @@ -2380,6 +2421,7 @@ int snd_usbmidi_create(struct snd_card *card, err = snd_usbmidi_detect_per_port_endpoints(umidi, endpoints); break; case QUIRK_MIDI_CH345: + umidi->usb_protocol_ops = &snd_usbmidi_ch345_broken_sysex_ops; err = snd_usbmidi_detect_per_port_endpoints(umidi, endpoints); break; default: