[ALSA] usb-audio - use proper interval between synchronization packets
Clemens Ladisch [Mon, 2 May 2005 06:53:46 +0000 (08:53 +0200)]
USB generic driver
Add sanity checks when reading the bRefresh value, and actually use it
for the synchronization packets instead of polling at 1000 Hz.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>

sound/usb/usbaudio.c

index e759b73..e1a648d 100644 (file)
@@ -1051,10 +1051,7 @@ static int init_substream_urbs(snd_usb_substream_t *subs, unsigned int period_by
                        u->urb->pipe = subs->syncpipe;
                        u->urb->transfer_flags = URB_ISO_ASAP;
                        u->urb->number_of_packets = u->packets;
-                       if (snd_usb_get_speed(subs->dev) == USB_SPEED_HIGH)
-                               u->urb->interval = 8;
-                       else
-                               u->urb->interval = 1;
+                       u->urb->interval = 1 << subs->syncinterval;
                        u->urb->context = u;
                        u->urb->complete = snd_usb_complete_callback(snd_complete_sync_urb);
                }
@@ -1272,7 +1269,12 @@ static int set_format(snd_usb_substream_t *subs, struct audioformat *fmt)
                        subs->syncpipe = usb_rcvisocpipe(dev, ep);
                else
                        subs->syncpipe = usb_sndisocpipe(dev, ep);
-               subs->syncinterval = get_endpoint(alts, 1)->bRefresh;
+               if (get_endpoint(alts, 1)->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
+                   get_endpoint(alts, 1)->bRefresh >= 1 &&
+                   get_endpoint(alts, 1)->bRefresh <= 9)
+                       subs->syncinterval = get_endpoint(alts, 1)->bRefresh;
+               else
+                       subs->syncinterval = 1;
        }
 
        /* always fill max packet size */