[Buildroot] can not open ttyUSB0

Stefan Fröberg stefan.froberg at petroprogram.com
Wed Jan 30 12:19:42 UTC 2013


Hi Adeel

30.1.2013 8:27, Adeel Nafis kirjoitti:
> Dear All,
> I have a kit2416 (http://www.armdesigner.com/KIT2416.html) module with
> Samsung ARM926EJS*. *I have configured buildroot with static device
> table, and added the ttyUSB0,1,2,3 to with major 188 and minor 0,1,2,3
> to the file.
> I also added the line to /etc/fstab
>
> none    /dev/bus/usb    usbfs    defaults,devmode=0666    0    0
>
> After attaching a 3G Modem USB  I am able to successfully use
> 'usb_modeswitch" and get the device to switch with messages indicating
> that the device is connected to /dev/ttyUSB0,1,2. However, after this
> I can not open the /dev/ttyUSBx any more. If i use gnokii for arm it
> prints out some messages indicating that it failed to open the port.
>
> Gnokii output
> GNOKII Version 0.6.26
> Gnokii serial_open: open: No such device        <----- the port here
> is set to /dev/ttyUSB0
> Couldn't open ATBUS device: No such device
> Telephone interface init failed: Command failed.
> Quitting.
> Cannot unlock device.
> Command failed.
>
> I have tested the thing out with Ubuntu for arm on the same platform
> and can verify that it works.
>
> If I do `cat /dev/bus/usb/devices` output is
> # cat /dev/bus/usb/devices
>
> T:  Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#=  1 Spd=12  MxCh= 2
> B:  Alloc=  0/900 us ( 0%), #Int=  0, #Iso=  0
> D:  Ver= 1.10 Cls=09(hub  ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
> P:  Vendor=0000 ProdID=0000 Rev= 2.06
> S:  Manufacturer=Linux 2.6.21.5-cfs-v19 ohci_hcd
> S:  Product=S3C24XX OHCI
> S:  SerialNumber=s3c24xx
> C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=  0mA
> I:* If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub
> E:  Ad=81(I) Atr=03(Int.) MxPS=   2 Ivl=255ms
>
> T:  Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  3 Spd=12  MxCh= 0
> D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
> P:  Vendor=12d1 ProdID=1446 Rev= 0.00
> S:  Manufacturer=HUAWEI Technology
> S:  Product=HUAWEI Mobile
> S:  SerialNumber=1234567890ABCDEF
> C:* #Ifs= 2 Cfg#= 1 Atr=e0 MxPwr=500mA
> I:* If#= 0 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=(none)
> E:  Ad=81(I) Atr=02(Bulk) MxPS=  64 Ivl=0ms
> E:  Ad=01(O) Atr=02(Bulk) MxPS=  64 Ivl=0ms
> I:* If#= 1 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=usb-storage
> E:  Ad=02(O) Atr=02(Bulk) MxPS=  64 Ivl=0ms
> E:  Ad=82(I) Atr=02(Bulk) MxPS=  64 Ivl=0ms
>
>
> Any pointers?
>
>
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If I remember correctly those Huawei modems (I had one once) detect
allright at the boot but then they switch to usb storage because all(?)
3G modems have some memory reserved
to work as regular USB stick (all "CD-ROM" in windows).

So it might be that your modem detected ok at boot but then immediately
switched to that storage mode and you have to switch it back by playing
with usb_modeswitch
command parameters.

There is a meniton of that in "Troubleshooting, Kernel related issues"
in usb_modeswitch makers pages:

http://www.draisberghof.de/usb_modeswitch/#trouble

Regards
Stefan



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