The USB composite framework [LWN.net]

The USB composite framework

Posted Nov 5, 2012 22:58 UTC (Mon) by DABraun (guest, #39500)
Parent article: The USB composite framework

What is it about the Device Descriptor that makes it a composite device?

I created one of your composite devices on a Freescale based embedded system and looked at the device descriptor on the host (Windows) side and there are a number of "Unknown Descriptors" looking like
Unknown Descriptor:
bDescriptorType: 0x24
bLength: 0x05
05 24 00 10 01
(this is from MS usbview.exe utility)
What are these? The descriptor type 0x24 is from the USB 3 spec and is called "USB_DT_PIPE_USAGE" - I searched for this in the 2.6.29.4 sources and couldn't find any references. This leads me to think some trash has been included in the device decriptors. But then again I could have missed something.

Any ideas?

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The USB composite framework

Posted Nov 5, 2012 23:48 UTC (Mon) by jimparis (subscriber, #38647) [Link]

I think USB_DT_PIPE_USAGE is related to UAS (USB Attached SCSI). Maybe "lsusb -vvv" on a Linux host can parse the descriptor better.