From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964907AbbLXPoh (ORCPT ); Thu, 24 Dec 2015 10:44:37 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:51366 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752006AbbLXPmc (ORCPT ); Thu, 24 Dec 2015 10:42:32 -0500 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Takashi Iwai" , "Clemens Ladisch" Date: Thu, 24 Dec 2015 15:37:42 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 04/77] ALSA: usb-audio: prevent CH345 multiport output SysEx corruption In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.247 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.2.75-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Clemens Ladisch commit 1ca8b201309d842642f221db7f02f71c0af5be2d upstream. The CH345 USB MIDI chip has two output ports. However, they are multiplexed through one pin, and the number of ports cannot be reduced even for hardware that implements only one connector, so for those devices, data sent to either port ends up on the same hardware output. This becomes a problem when both ports are used at the same time, as longer MIDI commands (such as SysEx messages) are likely to be interrupted by messages from the other port, and thus to get lost. It would not be possible for the driver to detect how many ports the device actually has, except that in practice, _all_ devices built with the CH345 have only one port. So we can just ignore the device's descriptors, and hardcode one output port. Signed-off-by: Clemens Ladisch Signed-off-by: Takashi Iwai Signed-off-by: Ben Hutchings --- sound/usb/midi.c | 3 +++ sound/usb/quirks-table.h | 11 +++++++++++ sound/usb/quirks.c | 1 + sound/usb/usbaudio.h | 1 + 4 files changed, 16 insertions(+) --- a/sound/usb/midi.c +++ b/sound/usb/midi.c @@ -2215,6 +2215,9 @@ int snd_usbmidi_create(struct snd_card * err = snd_usbmidi_detect_per_port_endpoints(umidi, endpoints); break; + case QUIRK_MIDI_CH345: + err = snd_usbmidi_detect_per_port_endpoints(umidi, endpoints); + break; default: snd_printd(KERN_ERR "invalid quirk type %d\n", quirk->type); err = -ENXIO; --- a/sound/usb/quirks-table.h +++ b/sound/usb/quirks-table.h @@ -2611,6 +2611,17 @@ YAMAHA_DEVICE(0x7010, "UB99"), .idProduct = 0x1020, }, +/* QinHeng devices */ +{ + USB_DEVICE(0x1a86, 0x752d), + .driver_info = (unsigned long) &(const struct snd_usb_audio_quirk) { + .vendor_name = "QinHeng", + .product_name = "CH345", + .ifnum = 1, + .type = QUIRK_MIDI_CH345 + } +}, + /* KeithMcMillen Stringport */ { USB_DEVICE(0x1f38, 0x0001), --- a/sound/usb/quirks.c +++ b/sound/usb/quirks.c @@ -311,6 +311,7 @@ int snd_usb_create_quirk(struct snd_usb_ [QUIRK_MIDI_CME] = create_any_midi_quirk, [QUIRK_MIDI_AKAI] = create_any_midi_quirk, [QUIRK_MIDI_FTDI] = create_any_midi_quirk, + [QUIRK_MIDI_CH345] = create_any_midi_quirk, [QUIRK_AUDIO_STANDARD_INTERFACE] = create_standard_audio_quirk, [QUIRK_AUDIO_FIXED_ENDPOINT] = create_fixed_stream_quirk, [QUIRK_AUDIO_EDIROL_UAXX] = create_uaxx_quirk, --- a/sound/usb/usbaudio.h +++ b/sound/usb/usbaudio.h @@ -81,6 +81,7 @@ enum quirk_type { QUIRK_MIDI_AKAI, QUIRK_MIDI_US122L, QUIRK_MIDI_FTDI, + QUIRK_MIDI_CH345, QUIRK_AUDIO_STANDARD_INTERFACE, QUIRK_AUDIO_FIXED_ENDPOINT, QUIRK_AUDIO_EDIROL_UAXX,