[ALSA] usb-audio: work around broken M-Audio MidiSport Uno firmware
The firmware of the M-Audio USB Uno MIDI Interface has, at least in
hardware revision 1.25, a bug that garbles its USB output. When it
receives a Note On MIDI message that uses running status, the resulting
USB MIDI packet has a wrong CIN (4 instead of 9) and a wrong length
(2 bytes, the status byte is still missing).
This patch adds a workaround to track the CINs and the MIDI messages of
received USB MIDI packets to detect whether a packet with CIN 4 is a
correct SysEx packet or a buggy running status packet.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Jaroslav Kysela <perex@suse.cz>
diff --git a/sound/usb/usbmidi.c b/sound/usb/usbmidi.c
index 24f5a26..911f448 100644
--- a/sound/usb/usbmidi.c
+++ b/sound/usb/usbmidi.c
@@ -1,7 +1,7 @@
/*
* usbmidi.c - ALSA USB MIDI driver
*
- * Copyright (c) 2002-2005 Clemens Ladisch
+ * Copyright (c) 2002-2007 Clemens Ladisch
* All rights reserved.
*
* Based on the OSS usb-midi driver by NAGANO Daisuke,
@@ -145,6 +145,7 @@
struct urb* urb;
struct usbmidi_in_port {
struct snd_rawmidi_substream *substream;
+ u8 running_status_length;
} ports[0x10];
u8 seen_f5;
u8 error_resubmit;
@@ -366,6 +367,46 @@
}
/*
+ * Buggy M-Audio device: running status on input results in a packet that has
+ * the data bytes but not the status byte and that is marked with CIN 4.
+ */
+static void snd_usbmidi_maudio_broken_running_status_input(
+ struct snd_usb_midi_in_endpoint* ep,
+ uint8_t* buffer, int buffer_length)
+{
+ int i;
+
+ for (i = 0; i + 3 < buffer_length; i += 4)
+ if (buffer[i] != 0) {
+ int cable = buffer[i] >> 4;
+ u8 cin = buffer[i] & 0x0f;
+ struct usbmidi_in_port *port = &ep->ports[cable];
+ int length;
+
+ length = snd_usbmidi_cin_length[cin];
+ if (cin == 0xf && buffer[i + 1] >= 0xf8)
+ ; /* realtime msg: no running status change */
+ else if (cin >= 0x8 && cin <= 0xe)
+ /* channel msg */
+ port->running_status_length = length - 1;
+ else if (cin == 0x4 &&
+ port->running_status_length != 0 &&
+ buffer[i + 1] < 0x80)
+ /* CIN 4 that is not a SysEx */
+ length = port->running_status_length;
+ else
+ /*
+ * All other msgs cannot begin running status.
+ * (A channel msg sent as two or three CIN 0xF
+ * packets could in theory, but this device
+ * doesn't use this format.)
+ */
+ port->running_status_length = 0;
+ snd_usbmidi_input_data(ep, cable, &buffer[i + 1], length);
+ }
+}
+
+/*
* Adds one USB MIDI packet to the output buffer.
*/
static void snd_usbmidi_output_standard_packet(struct urb* urb, uint8_t p0,
@@ -525,6 +566,12 @@
.output_packet = snd_usbmidi_output_midiman_packet,
};
+static struct usb_protocol_ops snd_usbmidi_maudio_broken_running_status_ops = {
+ .input = snd_usbmidi_maudio_broken_running_status_input,
+ .output = snd_usbmidi_standard_output,
+ .output_packet = snd_usbmidi_output_standard_packet,
+};
+
/*
* Novation USB MIDI protocol: number of data bytes is in the first byte
* (when receiving) (+1!) or in the second byte (when sending); data begins
@@ -1606,6 +1653,9 @@
switch (quirk ? quirk->type : QUIRK_MIDI_STANDARD_INTERFACE) {
case QUIRK_MIDI_STANDARD_INTERFACE:
err = snd_usbmidi_get_ms_info(umidi, endpoints);
+ if (chip->usb_id == USB_ID(0x0763, 0x0150)) /* M-Audio Uno */
+ umidi->usb_protocol_ops =
+ &snd_usbmidi_maudio_broken_running_status_ops;
break;
case QUIRK_MIDI_FIXED_ENDPOINT:
memcpy(&endpoints[0], quirk->data,