Re: State of highspeed usb2 audio?

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On 12.04.2012 21:24, alexander wrote:
> On 04/12/2012 09:59 PM, Daniel Mack wrote:
>> On 08.01.2012 16:07, alexander wrote:
>>> So again, exactly what is the state of usb2 audio class compliance? I've
>>> asked around in many places now and noone seems to know. I read
>>> somewhere that it's spotty at best and other places that it has just
>>> been implemented, seems like noone knows for sure.. So another question
>>> arises, is it a hard thing to do?
>> Sorry for the late response.
>> Support for v2 is fairly complete, with the exception of some clocking
>> features that have not been observed "in the wild". Is you issue already
>> solved?
>> If not, can I ask you to build a 3.4.0 kernel and apply this patch on
>> top? I just submitted a new version of a rework patch that changes a lot
>> things around USB packet handling in the snd-usb driver.
>> I would be interested wether this changes anything for your card.
>> Daniel
> Hooray! That's a very late response ;D nonetheless, it's a response and 
> I'm very happy! I've never compiled a kernel before but I could give it 
> a try.. Have you seen my alsa bug report? 
> I just 
> noticed now as I write that a reporter named bjorn has a hack for it 
> that seems to work. Reporter 'shal' also gets the same dmesg error, but 
> I dont know if it's the same card or not.. He says he has more linux 
> background tho so he might be more effective with the kernel compiling etc.

Ah ok. Saw the patch and added a new one that implements the quirk for
newer kernels. I also attached the patch here.

Once you managed to build the kernel (there are plenty of good HOWTOs
out there), let me know the result. You can apply the other patch
additionally (from the gist location I pointed you to), but that should
be optional.

diff --git a/sound/usb/stream.c b/sound/usb/stream.c
index 6b7d7a2..11b5bd1 100644
--- a/sound/usb/stream.c
+++ b/sound/usb/stream.c
@@ -450,6 +450,10 @@ int snd_usb_parse_audio_interface(struct snd_usb_audio *chip, int iface_no)
 				fp->ep_attr |= USB_ENDPOINT_SYNC_SYNC;
+		case USB_ID(0x0926, 0x0202): /* SoundDevices USBPre2 */
+			/* force 4-byte maxpacksize in high-speed mode */
+			if (snd_usb_get_speed(dev) == USB_SPEED_HIGH)
+				fp->maxpacksize = 4;
 		/* ok, let's parse further... */
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