[ALSA] usb-audio: add workaround for broken E-Mu frequency feedback

Add a workaround for the feedback pipe of E-Mu 0202/0404 USB devices
that reports the number of samples per packet instead of the number of
samples per microframe.

Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c
index 8fa93566570272036365009776ec0fa952c1303d..675672f313be322138c8902ce95a889a78c72782 100644 (file)
--- a/sound/usb/usbaudio.c
+++ b/sound/usb/usbaudio.c
@@ -479,6 +479,33 @@ static int retire_playback_sync_urb_hs(struct snd_usb_substream *subs,
        return 0;
 }
 
+/*
+ * process after E-Mu 0202/0404 high speed playback sync complete
+ *
+ * These devices return the number of samples per packet instead of the number
+ * of samples per microframe.
+ */
+static int retire_playback_sync_urb_hs_emu(struct snd_usb_substream *subs,
+                                          struct snd_pcm_runtime *runtime,
+                                          struct urb *urb)
+{
+       unsigned int f;
+       unsigned long flags;
+
+       if (urb->iso_frame_desc[0].status == 0 &&
+           urb->iso_frame_desc[0].actual_length == 4) {
+               f = combine_quad((u8*)urb->transfer_buffer) & 0x0fffffff;
+               f >>= subs->datainterval;
+               if (f >= subs->freqn - subs->freqn / 8 && f <= subs->freqmax) {
+                       spin_lock_irqsave(&subs->lock, flags);
+                       subs->freqm = f;
+                       spin_unlock_irqrestore(&subs->lock, flags);
+               }
+       }
+
+       return 0;
+}
+
 /* determine the number of frames in the next packet */
 static int snd_usb_audio_next_packet_size(struct snd_usb_substream *subs)
 {
@@ -2219,10 +2246,17 @@ static void init_substream(struct snd_usb_stream *as, int stream, struct audiofo
        subs->stream = as;
        subs->direction = stream;
        subs->dev = as->chip->dev;
-       if (snd_usb_get_speed(subs->dev) == USB_SPEED_FULL)
+       if (snd_usb_get_speed(subs->dev) == USB_SPEED_FULL) {
                subs->ops = audio_urb_ops[stream];
-       else
+       } else {
                subs->ops = audio_urb_ops_high_speed[stream];
+               switch (as->chip->usb_id) {
+               case USB_ID(0x041e, 0x3f02): /* E-Mu 0202 USB */
+               case USB_ID(0x041e, 0x3f04): /* E-Mu 0404 USB */
+                       subs->ops.retire_sync = retire_playback_sync_urb_hs_emu;
+                       break;
+               }
+       }
        snd_pcm_set_ops(as->pcm, stream,
                        stream == SNDRV_PCM_STREAM_PLAYBACK ?
                        &snd_usb_playback_ops : &snd_usb_capture_ops);