On Fri, 29 Oct 2010, [UTF-8] Sven Köhler wrote: > Am 28.10.2010 17:33, schrieb Greg KH: > > On Thu, Oct 28, 2010 at 03:54:00PM +0200, Sven Köhler wrote: > >> Hi, > >> > >> recently, I noticed that I wasn't able to flash my Lego NXT brick > >> anymore. As soon as the device is plugged in, cdc_acm claims the usb > >> device and provides a ttyACM*-device. > >> > >> Now I could rewrite some bits of our software and use the ttyACM*-device > >> to talk to the NXT. But this seems wrong to more for several reasons: > >> > >> If the Lego NXT is in firmware update mode, the SAM-BA program is run by > >> the arm CPU. It's part of the CPU, non-changeable, and it doesn't > >> understand any AT commands at all. So it is not a modem, and as far as I > >> understand, the policy is that device should be blacklisted. > > > > Then why is it showing up to the host as a cdc-acm device? Is it lying? > > If so, why? It seems like someone went through a lot of work to get it > > to look like a cdc-acm device, why not operate it that way? > > Attached you find the output of lsusb for the device. > Yes, it does claim to be a CDC device. In dmesg, cdc_acm correctly > remarks that this device is not a modem. > > But out of interest, I would like to investigate the reason for why > cdc_acm now claims that device. It definitely didn't do so in the past. > I tested a livecd with kernel 2.6.32. cdc_acm was showing no interest in > that device. > > The decision, whether cdc_acm claims a device, is made in > drivers/usb/class/cdc_acm.c, right? Is anybody aware of changes that > caused this change in behaviour of cdc_acm? The change you're looking for is here (USB: cdc-acm: Add pseudo modem without AT command capabilities): http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=5b239f0aebd4dd6f85b13decf5e18e86e35d57f0 > I can confirm, that the device works. I had too trick the official Atmel > SAM-BA software into using a ttyACM* device (it only looks for ttyUSB* > devices) but everything seemed to work fine. > (Except that modem-manager was probing the device) Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
