Am 28.10.2010 17:33, schrieb Greg KH: > On Thu, Oct 28, 2010 at 03:54:00PM +0200, Sven KÃhler 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? 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) Regards, Sven
Bus 002 Device 007: ID 03eb:6124 Atmel Corp. at91sam SAMBA bootloader
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 1.10
bDeviceClass 2 Communications
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 8
idVendor 0x03eb Atmel Corp.
idProduct 0x6124 at91sam SAMBA bootloader
bcdDevice 1.10
iManufacturer 0
iProduct 0
iSerial 0
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 67
bNumInterfaces 2
bConfigurationValue 1
iConfiguration 0
bmAttributes 0xc0
Self Powered
MaxPower 0mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 1
bInterfaceClass 2 Communications
bInterfaceSubClass 2 Abstract (modem)
bInterfaceProtocol 0 None
iInterface 0
CDC Header:
bcdCDC 1.10
CDC ACM:
bmCapabilities 0x00
CDC Union:
bMasterInterface 0
bSlaveInterface 1
CDC Call Management:
bmCapabilities 0x00
bDataInterface 1
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x83 EP 3 IN
bmAttributes 3
Transfer Type Interrupt
Synch Type None
Usage Type Data
wMaxPacketSize 0x0008 1x 8 bytes
bInterval 255
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 1
bAlternateSetting 0
bNumEndpoints 2
bInterfaceClass 10 CDC Data
bInterfaceSubClass 0 Unused
bInterfaceProtocol 0
iInterface 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x01 EP 1 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x82 EP 2 IN
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0
Device Status: 0x0000
(Bus Powered)
Attachment:
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