180Mhz is minimal ARM clock required for USB 2.0

David Brownell david-b at pacbell.net
Mon Mar 26 11:04:13 CST 2007


On Friday 23 March 2007 6:18 pm, Andy Ngo wrote:
> Hi guys,
> 
> On a related USB item, can I built just "one" kernel image that can support
> either host or peripheral modes?  Our hardware engineer is planning to use a
> Xilinx FPGA register to select the termination for the USB host/client
> configuration.  Hence we can configure USB for host or client based on the
> value of the register.  We're not using OTG, but just either host or peripheral;
> we don't want 2 separate kernel images one for each mode.  Is this possible?

The latest code (linux-omap tree, with more patches than davinci-git)
should allow this ... configure it with OTG, disable the OTG whitelist,
and then the role is defined purely according to the ID sensing logic.

That ID-sensing seems flakey on DaVinci, but there's a workaround in
place.  At this point I'd not be surprised to start seeing issues
creep in which would prevent host-only or peripheral-only modes from
working ... that's just a heads-up, patches to address any such issues
should be straightforward.

- Dave



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