Re: [libusb] Open device on Android

[Antão A. <ant...@gm...>]

On Wed, Mar 16, 2016 at 12:54 AM Xiaofan Chen <xia...@gm...> wrote:

> On Tue, Mar 15, 2016 at 10:23 PM, Antão Almada <ant...@gm...>
> wrote:
> > I'm using the Gritzman fork (https://github.com/Gritzman/libusb), based
> on
> > the OPENNI fork, that fixes the known Android file descriptor and
> SELinux
> > issues. Root is not required.
>
> In any case, I do not think you should rely on this fork, the base
> version of libusb 1.0.9 is too old.
>

Unfortunately after all these years the official source still has no
support for the issues I mentioned previously.

My first plan was actually to use the official source but it crashs even
before I make any change.

I now suspect it's the only Android specific code in libusb that is making
it crash. It uses __android_log_write() instead of __android_log_print():
http://stackoverflow.com/questions/12752043/output-of-android-log-write-not-displayed-in-logcat

A problem I just found out on the Gritzman fork when I turned on
ENABLE_DEBUG_LOGGING.


> > I'm using Android USB Accessory mode where the connected device is
> > the host and implements Android Open Accessory (AOA). My app is not
> > running on the host and the issue now is that the device does not show
> > up in the device enumeration... :(
>
> In that case,your issue has nothing to do with libusb. libusb is only
> for the host side. But your Android device is not the host in this
> mode. You should forget about libusb in this case.
>

I don't believe that's true.

An Android accessory is available as a /dev/usb_accessory file:
https://books.google.pt/books?id=0cuQAwAAQBAJ&pg=PA93

It requires some changes on the backend but I'm sure it is possible.


> > I'm going through all this because using the Android public API I'm
> > getting too many ENODEV errors. Unfortunately this is a known
> >  Android bug (feature?) so I'm trying to find a workaround.
>
> You'd better debug your host device.
>

I've been debugging both the host and the client for quite some time.

https://code.google.com/p/android/issues/detail?id=20545&can=1&q=enodev&colspec=ID%20Status%20Priority%20Owner%20Summary%20Stars%20Reporter%20Opened

You'd better be sure about what you're saying before replying to emails on
the mailing list.


>
> --
> Xiaofan
>

--
Antao