Commit f167e1d0 authored by Clemens Ladisch's avatar Clemens Ladisch Committed by Jaroslav Kysela
Browse files

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: default avatarClemens Ladisch <clemens@ladisch.de>
Cc: <stable@kernel.org>
Signed-off-by: default avatarJaroslav Kysela <perex@perex.cz>
parent 9d4c7464

sound/usb/usbmidi.c

+15 −3
Original line number Diff line number Diff line
@@ -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,

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