On Wed, 14 Oct 2015 00:09:36 +0100
Adam Sampson <a...@offog.org> wrote:
> Hi all,
>
> What kernel config options do I need to turn on for OTG to work on the
> A20? It doesn't appear to be enabled in sunxi_defconfig or
> multi_v7_defconfig.
Hi,
Yes, indeed. Currently everyone needs to waste some time solving this
kernel config puzzle when enabling USB OTG support. And I'm embarrassed
to admit that it took me several hours until I got it working. If I
find some time for it, I might write a howto guide in the wiki. But
don't take this as a promise.
This is what I used for testing USB OTG on pcDuino2:
https://github.com/ssvb/linux-sunxi/commits/20151014-4.3.0-rc5-pcduino2-otg-test
It is based on the current 'sunxi-next' branch from
https://github.com/linux-sunxi/linux-sunxi and applies
a few patches on top of it.
This way I get the system successfully booting on pcDuino2 from NFS via
cdc_ether if a Micro-B cable is connected (that's the primary use case
for me). And if a USB OTG cable is connected, then it works as USB host.
The important parts were the CONFIG_MUSB_PIO_ONLY=y option (without
it enabled, I had DMA related errors in the kernel log) and the old
'sunxi: initialize pinctrl before module init, fix "could not find
pctldev for node %s, deferring probe"' patch from willswang (without
it, there were these "deferred probe" errors also making USB OTG fail).
> The patch below adds support for OTG for the pcDuino v3 Nano based on
> the schematic, and I've verified that PH4 is indeed the ID pin by
> reading it as a GPIO (it reads 0 with a host adaptor plugged in and 1
> with nothing plugged in), but trying various likely-looking config
> options hasn't resulted in it actually detecting devices, so I assume
> there's something I'm meant to have enabled that I haven't...
You can try to apply your patch to my test branch and check if it works.
Good luck.
--
Best regards,
Siarhei Siamashka
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