Re: [pyusb-users] USB topology

[Nicolas P. <nic...@aa...>]

Le 13/05/2016 à 16:39, Nicolas Pinault a écrit :
> Le 13/05/2016 à 15:10, Jeffrey Nichols a écrit :
>> On 5/13/2016 9:03 AM, Nicolas Pinault wrote:
>>> Le 12/05/2016 à 17:15, Wander Lairson Costa a écrit :
>>>> 2016-05-12 11:40 GMT-03:00 Nicolas Pinault<nic...@aa...>:
>>>>> Hi,
>>>>>
>>>>> Is it possible to retrieve USB bus topology with PyUSB ?
>>>>>
>>>> Yes, you will need to use the Device object "port_number" and "bus" properties.
>>> While it is enough for my application, I don't see how to 
>>> reconstruct the USB tree with just "port_number".
>> There's also "port_numbers", assuming you're using a somewhat recent 
>> libusb-1.0 version as your backend. Combine that with the bus 
>> attribute, and you can get a representation of the physical 
>> attachment point of the device.
> I already tried to use "port_numbers" but this field was always blank.
> After updating libusb-1.0, this field is not blank anymore.
>
> What  I don't understand is that bus/port_number numbers are not unique.
> On my system :
>   IdVendor8086 IdProduct=1E26 bus=1 Address=1 port=0
>   IdVendor8086 IdProduct=1E2D bus=2 Address=1 port=0
> * IdVendor0204 IdProduct=6025 bus=1 Address=6 port=1 ports = (1, 6, 1)
>   IdVendor0424 IdProduct=2513 bus=1 Address=2 port=6 ports = (1, 6)
> + IdVendor046D IdProduct=C061 bus=2 Address=5 port=1 ports = (1, 1)
>   IdVendor0529 IdProduct=0001 bus=1 Address=4 port=5 ports = (1, 5)
>   IdVendor2CFF IdProduct=0002 bus=1 Address=5 port=2 ports = (1, 6, 2)
>   IdVendor413C IdProduct=2107 bus=2 Address=2 port=2 ports = (1, 2)
> + IdVendor8087 IdProduct=0024 bus=2 Address=4 port=1 ports = (1,)
> * IdVendor8087 IdProduct=0024 bus=1 Address=3 port=1 ports = (1,)
>   IdVendor8564 IdProduct=4000 bus=3 Address=20 port=8 ports = (8,)
>   IdVendor8086 IdProduct=1E31 bus=3 Address=1 port=0
>
> The lines marked with a + or a * contains same bus/port_number numbers.
> Only port_numbers field is different.
> What does this mean ?
>
After sorting results and analysing further, I understand the whole picture.
port_numbers like (1,) references a hub
port_numbers like (1, 6, 2) indicate the full path to reach the device 
(root/hub/device)
port_number references the port number of the last hub the device is 
connected on..

Nicolas