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Author Topic: device enumeration: mandatory to query BOS descriptor ?  (Read 4935 times)

erdmann

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device enumeration: mandatory to query BOS descriptor ?
« on: September 29, 2016, 09:52:15 am »
In order to successfully enumerate a USB 3.x device attached to a USB 2.0 port (bcdUSB = 0x210), is it MANDATORY to query its BOS descriptor or is that optional ?
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Jan Axelson

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Re: device enumeration: mandatory to query BOS descriptor ?
« Reply #1 on: September 30, 2016, 08:32:53 pm »
No, the BOS descriptor was first defined in the USB 2.0 Link Power Management Addendum. USB 2.0 hosts that don't support Link Power Management have no reason to request BOS descriptors.
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