[U-Boot] [PATCH 2/3] Connect the AT91 UDC to USB CDC-ethernet support

[Remy Bohmer]

Hi,

2010/8/13 Reinhard Meyer <u-boot at emk-elektronik.de>:
> Dear Remy Bohmer,
>>>
>>> 3. I did not follow the whole USB patches, my concern is
>>> what touches AT91, but please explain to me what for we need
>>> a board under u-boot to be a USB device. Since u-boot per se
>>> is not multitasking how is the traffic handled while
>>> at the command prompt?
>>
>> There is no traffic handled while at the command prompt. It behaves
>> just like any other 'normal' network adapter.
>> So, it brings up a USB connection once you start a network action like
>> a ping or tftp command. Once that completes the link is brought down
>> again.
>
> If I understand the procedure correctly now, its as follows:
>
> Any client network command on u-boot's command prompt like ping, dhcp, tftp
> etc. will 'up' the USB Device...
> The host to which it is connected to will happily discover and enumerate
> a network adapter with MAC and IP addresses...

Correct.

> And the host will be the server for that command...

The procedure is initiated by U-boot, since that one is pulling the D+
resistor up and down.
Network traffic is of course bidirectional, so U-boot can initiate a
TFTP transfer when it is up.

Kind regards,

Remy