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[ALSA] usb-audio: work around broken M-Audio MidiSport Uno firmware

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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>
This commit is contained in:
Clemens Ladisch 2007-05-07 09:28:53 +02:00 committed by Jaroslav Kysela
parent a91214589e
commit d05cc10432
1 changed files with 51 additions and 1 deletions
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52
sound/usb/usbmidi.c
View file

@ -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 snd_usb_midi_in_endpoint {
struct urb* urb;
struct usbmidi_in_port {
struct snd_rawmidi_substream *substream;
u8 running_status_length;
} ports[0x10];
u8 seen_f5;
u8 error_resubmit;
@ -365,6 +366,46 @@ static void snd_usbmidi_midiman_input(struct snd_usb_midi_in_endpoint* ep,
}
}
/*
* 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.
*/
@ -525,6 +566,12 @@ static struct usb_protocol_ops snd_usbmidi_midiman_ops = {
.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 @@ int snd_usb_create_midi_interface(struct snd_usb_audio* chip,
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,