Re: [greybus-dev] virtual USB device

On Wed, Mar 22, 2017 at 04:39:01AM -0700, Greg Hazel wrote:

On Mar 22, 2017, at 4:33 AM, Greg KH <greg@kroah.com> wrote:

On Wed, Mar 22, 2017 at 04:29:09AM -0700, Greg Hazel wrote:



        On Mar 22, 2017, at 4:22 AM, Greg KH <greg@kroah.com> wrote:

        On Wed, Mar 22, 2017 at 04:19:30AM -0700, Greg Hazel wrote:

              What exactly do you have connected on the other side of that
            module
              uart?


            That UART is currently a TI SimpleLink/EasyLink. I’m also
            considering a
            slip-radio. These are relatively simple wrappers from radio to
            ethernet. Most
            importantly, I can only control the software on my side of the
            Greybus, so
            using bridged-phy to expose the UART as a tty would not enable
            me to use the
            tty on the other side…


        Well, go yell at your system engineers then, you can't fix broken
        systems by working around it in the kernel :)

        The greybus TTY interface should work just fine for you here,
        that's
        what it was designed for.


    I agree! However, yelling at large device manufacturers hasn’t proved
    fruitful for me.


Then provide a userspace application that interfaces with the tty device
and creates the connection that way?  There's no way that any random
network device showing up is going to work properly without some system
changes happening.

A userspace application could only provide a connection through VPN, which is encumbered with authorization dialogs and UI complications.

I agree.

The user-experience of a USB ethernet device connecting is much better (I’ve tried with a real adapter), so if that’s possible it does seem to be worth the effort.

Right now, no, there is no greybus network driver, sorry, so this isn't going to work, unless you get the USB host controller code to work, _AND_ have the correct USB networking driver loaded in the kernel.

That last point you might have a problem with on the system side as well.

    So taking the scenic route; is there a better way than cdc-evm?

It's a tty device, make it a tty device :)

Unfortunately this would mean asking users on the host side to unlock and root their device, which is very difficult and often against their warranty agreement.

Again, this isn't a kernel issue, but rather an issue with the system you are working on. Not much the kernel can do here, sorry :(

good luck!

greg k-h