Re: [alsa-devel] [PATCH 1/1] Allow any MIDI endpoint to drive use of interrupt transfer on Roland devices

On Sat, 10 Oct 2015 20:59:01 +0200, maillist@superlative.org wrote:

From: "Keith A. Milner" kamilner@superlative.org

Signed-off-by: Keith A. Milner maillist@superlative.org

The most important piece is missing -- why this change is needed at all. Could you give more detailed description?

thanks,

Takashi

diff --git a/sound/usb/midi.c b/sound/usb/midi.c index b901f46..52b8c72 100644 --- a/sound/usb/midi.c +++ b/sound/usb/midi.c @@ -1860,9 +1860,14 @@ static void snd_usbmidi_switch_roland_altsetting(struct snd_usb_midi* umidi)

hostif = &intf->altsetting[1]; intfd = get_iface_desc(hostif);

• /* If either or both of the endpoints support interrupt transfer,

• * then use the alternate setting
  

• */
  

  if (intfd->bNumEndpoints != 2 ||

•    (get_endpoint(hostif, 0)->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) != USB_ENDPOINT_XFER_BULK ||
  

•    (get_endpoint(hostif, 1)->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK) != USB_ENDPOINT_XFER_INT)
  

•    !((get_endpoint(hostif, 0)->bmAttributes
  

•      & USB_ENDPOINT_XFERTYPE_MASK) == USB_ENDPOINT_XFER_INT ||
  

•    (get_endpoint(hostif, 1)->bmAttributes
  

•      & USB_ENDPOINT_XFERTYPE_MASK) == USB_ENDPOINT_XFER_INT))
  

  return;

  snd_printdd(KERN_INFO "switching to altsetting %d with int ep\n",

-- 1.9.1