Patch "ALSA: usb-audio: prevent CH345 multiport output SysEx corruption" has been added to the 3.10-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    ALSA: usb-audio: prevent CH345 multiport output SysEx corruption

to the 3.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     alsa-usb-audio-prevent-ch345-multiport-output-sysex-corruption.patch
and it can be found in the queue-3.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 1ca8b201309d842642f221db7f02f71c0af5be2d Mon Sep 17 00:00:00 2001
From: Clemens Ladisch <clemens@ladisch.de>
Date: Sun, 15 Nov 2015 22:38:29 +0100
Subject: ALSA: usb-audio: prevent CH345 multiport output SysEx corruption

From: Clemens Ladisch <clemens@ladisch.de>

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 <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 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
@@ -2217,6 +2217,9 @@ 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
@@ -3041,6 +3041,17 @@ 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
@@ -313,6 +313,7 @@ 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
@@ -83,6 +83,7 @@ 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,


Patches currently in stable-queue which might be from clemens@ladisch.de are

queue-3.10/alsa-usb-audio-work-around-ch345-input-sysex-corruption.patch
queue-3.10/alsa-usb-audio-prevent-ch345-multiport-output-sysex-corruption.patch
queue-3.10/alsa-usb-audio-add-packet-size-quirk-for-the-medeli-dd305.patch