Thanks.
Do you mean that if "07 25 01 81 02 00 00" (Unrecognized) was
moved after the "Endpoint Descriptor", then the driver should
recognize it as some AudioControl Endpoint Descriptor (as
described in Table 4-21: Class-Specific AS Isochronous Audio Data
Endpoint Descripton in
http://www.usb.org/developers/devclass_docs/audio10.pdf)?
I have no idea if this is an easy modification (it does not sound
complex to me, but I never wrote firmware for USB audio devices!)
- Yves
On 22/04/2013 21:23, Torstein Hegge wrote:
On Mon, Apr 22, 2013 at 20:44:40 +0200, Daniel Mack wrote:
Also, the lsusb dumps don't contain a audio specific header descriptor,
which normally looks like this:
AudioControl Endpoint Descriptor:
bLength 7
bDescriptorType 37
bDescriptorSubtype 1 (EP_GENERAL)
bmAttributes 0x01
Sampling Frequency
bLockDelayUnits 0 Undefined
wLockDelay 0 Undefined
And without the "Sampling Frequency" bit in bmAttributes, the driver
will bail out early (clock.c):
I think it has the class specific endpoint descriptor, but it is in
front of the standard endpoint descriptor. From the 'lsusb -v':
AudioStreaming Interface Descriptor:
bLength 14
bDescriptorType 36
bDescriptorSubtype 2 (FORMAT_TYPE)
bFormatType 1 (FORMAT_TYPE_I)
bNrChannels 2
bSubframeSize 2
bBitResolution 16
bSamFreqType 2 Discrete
tSamFreq[ 0] 16000
tSamFreq[ 1] 48000
** UNRECOGNIZED: 07 25 01 81 02 00 00
Endpoint Descriptor:
bLength 9
bDescriptorType 5
bEndpointAddress 0x03 EP 3 OUT
bmAttributes 1
Transfer Type Isochronous
Synch Type None
Usage Type Data
wMaxPacketSize 0x00c0 1x 192 bytes
bInterval 1
bRefresh 0
bSynchAddress 0
The UNRECOGNIZED bit matches the missing AudioControl endpoint
descriptor.
Even if this is against the specification, devices that does this is out
there. I have seen the same thing on a Sennheiser BTD-500, but that only
supports one frequency, so I didn't hit this problem.
Torstein
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