How to force host mode for RPi Zero USB?
Hans Petter Selasky
hps at selasky.org
Thu Mar 28 14:44:00 UTC 2019
On 3/28/19 1:50 PM, Per Hedeland wrote:
> I have a 4-port USB hub that attaches directly to the RPi Zero board:
> http://www.uugear.com/product/zero4u/ . This seems to work fine on
> FreeBSD - as long as I have an OTG adapter/cable connected to the then
> otherwise unused data port on the Zero, which is a quite annoying
> requirement IMHO. Without it, the FreeBSD USB stack uses device mode
> (as described in the handbook), and (of course) doesn't even see the
> add-on hub.
> According to the hub documentation
> (http://www.uugear.com/doc/Zero4U_UserManual.pdf), "Linux" uses host
> mode by default, and requries a DT overlay to use device mode. The
> FreeBSD automatic switching is arguably more elegant, but is IMHO
> inferior in a case like this (it's of course also impossible to make
> any USB devices work when connected to the Zero data port *without* an
> OTG adapter/cable).
> So, as $SUBJECT - surely there is a way to force host mode?
You can add a "dr_mode" property to the DWC OTG driver instance and set
it to "host".
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