ALSA: usb-audio: reduce MIDI packet size to work around broken firmware
Clemens Ladisch [Mon, 15 Feb 2010 07:55:28 +0000 (08:55 +0100)]
Extend the list of devices whose firmware does not expect more than one
USB MIDI packet in one USB packet.

bug report: https://bugtrack.alsa-project.org/alsa-bug/view.php?id=3752

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Cc: <stable@kernel.org>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

sound/usb/usbmidi.c

index 6e89b83..aae50df 100644 (file)
@@ -1162,10 +1162,22 @@ static int snd_usbmidi_out_endpoint_create(struct snd_usb_midi* umidi,
                pipe = usb_sndintpipe(umidi->dev, ep_info->out_ep);
        else
                pipe = usb_sndbulkpipe(umidi->dev, ep_info->out_ep);
-       if (umidi->usb_id == USB_ID(0x0a92, 0x1020)) /* ESI M4U */
-               ep->max_transfer = 4;
-       else
+       switch (umidi->usb_id) {
+       default:
                ep->max_transfer = usb_maxpacket(umidi->dev, pipe, 1);
+               break;
+               /*
+                * Various chips declare a packet size larger than 4 bytes, but
+                * do not actually work with larger packets:
+                */
+       case USB_ID(0x0a92, 0x1020): /* ESI M4U */
+       case USB_ID(0x1430, 0x474b): /* RedOctane GH MIDI INTERFACE */
+       case USB_ID(0x15ca, 0x0101): /* Textech USB Midi Cable */
+       case USB_ID(0x15ca, 0x1806): /* Textech USB Midi Cable */
+       case USB_ID(0x1a86, 0x752d): /* QinHeng CH345 "USB2.0-MIDI" */
+               ep->max_transfer = 4;
+               break;
+       }
        for (i = 0; i < OUTPUT_URBS; ++i) {
                buffer = usb_buffer_alloc(umidi->dev,
                                          ep->max_transfer, GFP_KERNEL,