Re: usb 1-3: Product: BBC micro:bit CMSIS-DAP not recognised

[dima.pasechnik@cs.ox.ac.uk]

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On Mon, Dec 19, 2022 at 04:29:34PM +0000, dima.pasechnik@cs.ox.ac.uk wrote:
> On Mon, Dec 19, 2022 at 04:00:29PM +0100, Greg KH wrote:
> > On Mon, Dec 19, 2022 at 12:57:43PM +0000, dima.pasechnik@cs.ox.ac.uk wrote:
> > > this is a popular in UK education board: https://microbit.org/
> > > - the currently sold (Version 2) one. It does on the same USB 3 things:
> > >   mass storage, ACM, and serial. Serial appears unknown to the kernel.
> > > 
> > > With Linux kernel 6.0.8 on x86_54, and various USB serial drivers installed, upon plugging into USB
> > > port, I see in dmesg:
> > > 
> > > [45460.035306] usb 1-3: new full-speed USB device number 10 using xhci_hcd
> > > [45460.166959] usb 1-3: New USB device found, idVendor=0d28, idProduct=0204, bcdDevice=10.00
> > > [45460.166965] usb 1-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
> > > [45460.166967] usb 1-3: Product: BBC micro:bit CMSIS-DAP
> > > [45460.166968] usb 1-3: Manufacturer: Arm
> > > [45460.166970] usb 1-3: SerialNumber: 9905360200052833525e24a702a68552000000006e052820
> > > [45460.172168] usb-storage 1-3:1.0: USB Mass Storage device detected
> > > [45460.172538] scsi host1: usb-storage 1-3:1.0
> > > [45460.173203] cdc_acm 1-3:1.1: ttyACM0: USB ACM device
> > > [45460.175258] hid-generic 0003:0D28:0204.0005: hiddev96,hidraw0: USB HID v1.00 Device [Arm BBC micro:bit CMSIS-DAP] on usb-0000:00:14.0-3/input3
> > > [45460.175581] usbserial_generic 1-3:1.4: The "generic" usb-serial driver is only for testing and one-off prototypes.
> > > [45460.175585] usbserial_generic 1-3:1.4: Tell linux-usb@vger.kernel.org to add your device to a proper driver.
> > > [45460.175587] usbserial_generic 1-3:1.4: device has no bulk endpoints
> > > [45460.175818] usbserial_generic 1-3:1.5: The "generic" usb-serial driver is only for testing and one-off prototypes.
> > > [45460.175821] usbserial_generic 1-3:1.5: Tell linux-usb@vger.kernel.org to add your device to a proper driver.
> > > [45460.175823] usbserial_generic 1-3:1.5: generic converter detected
> > 
> > Is there some script adding this device id to the generic driver such
> > that you are binding to this device?  Did the script come with the
> > device?
> 
> It didn't bind to a /dev/ttyUSB* device, even if I manually loaded the corresponding modules.
> Then I read somewhere I had to do 
> 
>     echo 0d28 0204 >/sys/bus/usb-serial/drivers/generic/new_id
> 
> (the numbers there are VID and PID of the board)
> to make it recognisible by the driver.
> 
> Unfortunately I can't easily tell you how it behaved without it,
> as it seems to be impossible to remove things there :-(
> https://unix.stackexchange.com/questions/463291/how-to-remove-device-id-from-manually-entered-usb-serial-driver
> Can it be wiped by reinstalling the kernel? I can do this...

OK, I removed the "new_id" by kernel reinstall, and
now all I get is the following:

[  176.427839] usb 1-3: new full-speed USB device number 5 using xhci_hcd
[  176.558808] usb 1-3: New USB device found, idVendor=0d28, idProduct=0204, bcdDevice=10.00
[  176.558825] usb 1-3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[  176.558833] usb 1-3: Product: BBC micro:bit CMSIS-DAP
[  176.558839] usb 1-3: Manufacturer: Arm
[  176.558845] usb 1-3: SerialNumber: 9905360200052833525e24a702a68552000000006e052820
[  176.566864] hid-generic 0003:0D28:0204.0001: hiddev96,hidraw0: USB HID v1.00 Device [Arm BBC micro:bit CMSIS-DAP] on usb-0000:00:14.0-3/input3
[  177.727061] usb-storage 1-3:1.0: USB Mass Storage device detected
[  177.733180] scsi host0: usb-storage 1-3:1.0
[  177.733333] usbcore: registered new interface driver usb-storage
[  177.733607] cdc_acm 1-3:1.1: ttyACM0: USB ACM device
[  177.733646] usbcore: registered new interface driver cdc_acm
[  177.733648] cdc_acm: USB Abstract Control Model driver for USB modems and ISDN adapters
[  177.739250] usbcore: registered new interface driver uas
[  178.752970] scsi 0:0:0:0: Direct-Access     MBED     VFS              0.1  PQ: 0 ANSI: 2
[  178.759252] sd 0:0:0:0: [sda] 131200 512-byte logical blocks: (67.2 MB/64.1 MiB)
[  178.759440] sd 0:0:0:0: [sda] Write Protect is off
[  178.759443] sd 0:0:0:0: [sda] Mode Sense: 03 00 00 00
[  178.759611] sd 0:0:0:0: [sda] No Caching mode page found
[  178.759613] sd 0:0:0:0: [sda] Assuming drive cache: write through
[  178.769674]  sda:
[  178.769773] sd 0:0:0:0: [sda] Attached SCSI removable disk

As you see, no USB serial driver is loaded.
However, https://tech.microbit.org/software/daplink-interface/
tells you that there is a 2nd CPU on the board, aka "interface chip",
capable of UART.

If I manually load the driver:
# insmod /lib/modules/6.0.8-gentoo-x86_64/kernel/drivers/usb/serial/usbserial.ko vendor=0x0d28 product=0x0204
and re-insert the USB connector, I see dmesg log as in my previous
message, and indeed, /dev/ttyUSB0 appears.

Well, perhaps, it's all supposed to work without a kernel module, hard
to say. It's however confusing that a /dev/tty1 (or some other number)
appears, but it's totally non-transparent that it is a USB connection
(no reflection of it in dmesg).

HTH
Dmitrii


> 
> > How well does it work?  Why did the developer choose to use this generic
> > driver instead of a real one?
> I don't know, I followed the advice in dmesg, which sounds as if it's
> not a "real" driver.
> 
> Best,
> Dmitrii
> > 
> > > [45460.175905] usb 1-3: generic converter now attached to ttyUSB0
> > 
> > It is not unknown, seems to bind here, but does it work?
> > 
> > thanks,
> > 
> > greg k-h



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