sound: usb-audio: fix uninitialized variable with M-Audio MIDI interfaces

Fix the snd_usbmidi_create_endpoints_midiman() function, which forgot to
set the out_interval member of the endpoint info structure for Midiman/
M-Audio devices.  Since kernel 2.6.24, any non-zero value makes the
driver use interrupt transfers instead of bulk transfers.  With EHCI
controllers, these random interval values result in unbearably large
latencies for output MIDI transfers.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Reported-by: David <devurandom@foobox.com>
Tested-by: David <devurandom@foobox.com>
Cc: <stable@kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/usbmidi.c b/sound/usb/usbmidi.c
index 320641a..26bad37 100644 (file)
--- a/sound/usb/usbmidi.c
+++ b/sound/usb/usbmidi.c
@@ -1625,6 +1625,7 @@ static int snd_usbmidi_create_endpoints_midiman(struct snd_usb_midi* umidi,
        }
 
        ep_info.out_ep = get_endpoint(hostif, 2)->bEndpointAddress & USB_ENDPOINT_NUMBER_MASK;
+       ep_info.out_interval = 0;
        ep_info.out_cables = endpoint->out_cables & 0x5555;
        err = snd_usbmidi_out_endpoint_create(umidi, &ep_info, &umidi->endpoints[0]);
        if (err < 0)