ALSA: usb-audio: reduce MIDI packet size to work around broken firmware

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>

diff --git a/sound/usb/usbmidi.c b/sound/usb/usbmidi.c
index 6e89b83..aae50df 100644 (file)
--- a/sound/usb/usbmidi.c
+++ b/sound/usb/usbmidi.c
@@ -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,