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-rw-r--r--sound/usb/midi.c42
1 files changed, 42 insertions, 0 deletions
diff --git a/sound/usb/midi.c b/sound/usb/midi.c
index 966051f530bd..9123fc518f07 100644
--- a/sound/usb/midi.c
+++ b/sound/usb/midi.c
@@ -174,6 +174,8 @@ struct snd_usb_midi_in_endpoint {
u8 running_status_length;
} ports[0x10];
u8 seen_f5;
+ bool in_sysex;
+ u8 last_cin;
u8 error_resubmit;
int current_port;
};
@@ -465,6 +467,39 @@ static void snd_usbmidi_maudio_broken_running_status_input(
}
/*
+ * QinHeng CH345 is buggy: every second packet inside a SysEx has not CIN 4
+ * but the previously seen CIN, but still with three data bytes.
+ */
+static void ch345_broken_sysex_input(struct snd_usb_midi_in_endpoint *ep,
+ uint8_t *buffer, int buffer_length)
+{
+ unsigned int i, cin, length;
+
+ for (i = 0; i + 3 < buffer_length; i += 4) {
+ if (buffer[i] == 0 && i > 0)
+ break;
+ cin = buffer[i] & 0x0f;
+ if (ep->in_sysex &&
+ cin == ep->last_cin &&
+ (buffer[i + 1 + (cin == 0x6)] & 0x80) == 0)
+ cin = 0x4;
+#if 0
+ if (buffer[i + 1] == 0x90) {
+ /*
+ * Either a corrupted running status or a real note-on
+ * message; impossible to detect reliably.
+ */
+ }
+#endif
+ length = snd_usbmidi_cin_length[cin];
+ snd_usbmidi_input_data(ep, 0, &buffer[i + 1], length);
+ ep->in_sysex = cin == 0x4;
+ if (!ep->in_sysex)
+ ep->last_cin = cin;
+ }
+}
+
+/*
* CME protocol: like the standard protocol, but SysEx commands are sent as a
* single USB packet preceded by a 0x0F byte.
*/
@@ -650,6 +685,12 @@ static struct usb_protocol_ops snd_usbmidi_cme_ops = {
.output_packet = snd_usbmidi_output_standard_packet,
};
+static struct usb_protocol_ops snd_usbmidi_ch345_broken_sysex_ops = {
+ .input = ch345_broken_sysex_input,
+ .output = snd_usbmidi_standard_output,
+ .output_packet = snd_usbmidi_output_standard_packet,
+};
+
/*
* AKAI MPD16 protocol:
*
@@ -2292,6 +2333,7 @@ int snd_usbmidi_create(struct snd_card *card,
err = snd_usbmidi_detect_per_port_endpoints(umidi, endpoints);
break;
case QUIRK_MIDI_CH345:
+ umidi->usb_protocol_ops = &snd_usbmidi_ch345_broken_sysex_ops;
err = snd_usbmidi_detect_per_port_endpoints(umidi, endpoints);
break;
default: