From: Clemens Ladisch <clemens@ladisch.de>
Date: Sun, 15 Nov 2015 21:38:29 +0000 (+0100)
Subject: ALSA: usb-audio: prevent CH345 multiport output SysEx corruption
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=88ab73208769677b3935d747a43aab1213d15d39;p=GitHub%2Fmt8127%2Fandroid_kernel_alcatel_ttab.git

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

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>
---

diff --git a/sound/usb/midi.c b/sound/usb/midi.c
index 13a27e66e179..736783b9d1a2 100644
--- a/sound/usb/midi.c
+++ b/sound/usb/midi.c
@@ -2215,6 +2215,9 @@ int snd_usbmidi_create(struct snd_card *card,
 		if (err < 0)
 			break;
 
+		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:
diff --git a/sound/usb/quirks-table.h b/sound/usb/quirks-table.h
index 45d586b6e8b5..9ec5ce4e35fb 100644
--- 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),
diff --git a/sound/usb/quirks.c b/sound/usb/quirks.c
index 734c6579b194..94cd28c2bd8d 100644
--- a/sound/usb/quirks.c
+++ b/sound/usb/quirks.c
@@ -313,6 +313,7 @@ int snd_usb_create_quirk(struct snd_usb_audio *chip,
 		[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,
diff --git a/sound/usb/usbaudio.h b/sound/usb/usbaudio.h
index bc43bcaddf4d..d6f3fefc882f 100644
--- 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,