[Arm-netbook] USB console idea

[Alejandro Mery]

On Tue, Mar 6, 2012 at 14:05, Bari Ari <bari at onelabs.com> wrote:
> On 03/06/2012 06:20 AM, lkcl luke wrote:
>> 2012/3/6 Henrik Nordström<henrik at henriknordstrom.net>:
>>> Was thinking why not use the USB for console?
>>
> Do any of the ARM SOC USB ports support the EHCI Debug Port ?
>
> In the x86 world a new USB debug class was started a few years ago since
> serial was depreciated and disappeared from most chipsets.
>
> " The debug port provides a mode of operation that requires neither RAM
> nor a full USB stack. A handful of registers in the EHCI controller PCI
> configuration and BAR address space are used for all communication. All
> three transfer types are supported (OUT/SETUP/IN) but transfers can only
> be a maximum of 8 bytes and only one specific physical USB port can be
> used. A Debug Class compliant device is the only supported USB function
> that can be communicated with."
>
> http://www.coreboot.org/EHCI_Debug_Port
>
> Has code examples for support and detection.

https://github.com/amery/linux-allwinner/blob/allwinner-v3.0-android/drivers/usb/host/ehci_sun4i.c
?