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[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>
This commit is contained in:
Clemens Ladisch 2008-02-25 11:01:00 +01:00 committed by Takashi Iwai
parent ee47fd12d7
commit d513202efd
1 changed files with 36 additions and 2 deletions
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38
sound/usb/usbaudio.c
View File

@ -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);