[patch 035/114] sound: usb-audio: fix uninitialized variable with M-Audio MIDI interfaces

Greg KH
2009-03-14T01:32:57Z

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2.6.28-stable review patch. If anyone has any objections, please let us know.

------------------

From: Clemens Ladisch <clemens@ladisch.de>

commit e156ac4c571e3be741bc411e58820b74a9295c72 upstream.

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>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
sound/usb/usbmidi.c | 1 +
1 file changed, 1 insertion(+)

--- a/sound/usb/usbmidi.c
+++ b/sound/usb/usbmidi.c
@@ -1628,6 +1628,7 @@ static int snd_usbmidi_create_endpoints_
}

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)