Re: [gentoo-user] USB mobile phone connection..

[Digby Tarvin]

Hi James,

Thanks for going to all the trouble of testing out the phone
operation on your SuSE machine. I havn't had any breakthrough
yet, but your help has given me the confidence to persevere..

On Wed, Nov 02, 2005 at 06:40:11AM -0500, James Hiscock wrote:
> > I've just tried to use moto4lin with a Motorola Razr. It starts as with
> > yours, but when I click "Switch to P2K", /dev/ttyACM0 disappears! nothing
> > works after that until I disconnect and reconnect the phone, at which
> > point I am back in AT mode and it all starts again.
>
> That's what was happening for me for several hours until it magically
> started working... I honestly don't know what the heck changed. But
> once it decided to work, it works consistently.

It also sounds very much like what I am seeing. My /dev/usb/acm/0
disappears the first time it is accessed (either by moto4lin or by
just echoing anything to it), followed by a message along the lines
of
	usb 1-1: USB disconnect, address 17
in /var/log/messages

So far I havn't managed to get it into a mode where it works more
sucessfully.

I have noticed that on connection I sometimes get:
 usb 1-1: new full speed USB device using uhci_hcd and address 5
 usb 1-1: device descriptor read/64, error -71
 usb 1-1: device descriptor read/64, error -71
 usb 1-1: new full speed USB device using uhci_hcd and address 6
 cdc_acm 1-1:1.0: ttyACM0: USB ACM device
whereas on other occasions I get:
 usb 1-1: new full speed USB device using uhci_hcd and address 16
 usb 1-1: device descriptor read/64, error -71
 usb 1-1: device descriptor read/64, error -71
 usb 1-1: new full speed USB device using uhci_hcd and address 17
 usb 1-1: device descriptor read/64, error -71
 cdc_acm 1-1:1.0: ttyACM0: USB ACM device
ie sometimes 2 descriptor read failures, sometimes 3.

so perhaps there is something a bit flakey in there that at some point
might just start working.

Anyone else seen these sort of error messages on plug-in? I'm really
not sure what they are telling me. I can't even find the error message
in the source. The closest I have found is in linux/drivers/usb/core/hub.c:
 dev_err(&udev->dev, "device descriptor read/%s, error %d\n", "all", retval);
but the '%s' seems hard wired to produce the string "all" rather than 64,
unless dev_err is doing something funny with its 3rd arg.

> There's a note in the moto4lin wiki specifically for Razr phones
> (http://moto4lin.sourceforge.net/wiki/Razr_V3) that says that it's
> inconsistent, and you may need to run
>
> echo AT+MODE=8 > /dev/ttyACM0
>
> When I was doing that last night on my laptop, the first time would
> work, and the second time it removed the device... I honestly don't
> know what the heck is going on with this program, but it _is_ a pretty
> early release... <shrug>

I get the device disappearing every time I attempt this. My gut feeling
is that the problem has nothing to do with moto4lin. After all, when I
am using echo it isn't even running.

I suspect it is more a compatability issue between the Linux USB/ACM
code and the Motorola gadget code.

> There isn't much info for the C380 in the wiki, other than the
> settings that should be used (which are the defaults)...

Yes, although it is listed as one of the models that work, so I assume
somebody must have managed to get it to go.

I still have to try tweaking the kernel USB related config parameters, but
if that doesn't help, I suspect I am going to have to bite the bullet and
try and find my way around the USB driver code. Anybody know of any good
references on USB protocols and drivers?

Regards,
DigbyT
-- 
Digby R. S. Tarvin                                             digbyt@××××××.com
http://www.digbyt.com
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