qmi_wwan on Huawei E398

qmi_wwan on Huawei E398

[Cedric Jehasse]

Hi,

I'm trying to use qmi on an Huawei E398 dongle with ofono on a 3.7.1
kernel. (this works with a 3.5.0 kernel)
ofono looks for the class/subclass/protocol of the parent
usb_interface device for the qmi_wwan and cdc_wdm devices. This must
match with ff/01/08 and ff/01/09 Cls/Sub/Prot.

Below is a trace of the udev events and usb-device output for a 3.5.0
and 3.7.1 kernel. The difference is in the parent devices for wwan0
and cdc-wdm0.
The parent device for wwan0 is on a 3.7.1 kernel is If3. Is this normal?

* 3.5.0:
KERNEL[201.262240] add
/devices/pci0000:00/0000:00:1d.7/usb2/2-6/2-6:1.3/usb/cdc-wdm0 (usb)
KERNEL[201.347292] add
/devices/pci0000:00/0000:00:1d.7/usb2/2-6/2-6:1.4/net/wwan0 (net)

T:  Bus=02 Lev=01 Prnt=01 Port=05 Cnt=01 Dev#=  4 Spd=480 MxCh= 0
D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=12d1 ProdID=150a Rev=00.00
S:  Manufacturer=Huawei Technologies
S:  Product=HUAWEI Mobile
S:  SerialNumber=1234567890ABCDEF
C:  #Ifs= 7 Cfg#= 1 Atr=c0 MxPwr=500mA
I:  If#= 0 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=01 Prot=01 Driver=option
I:  If#= 1 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=01 Prot=02 Driver=option
I:  If#= 2 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=01 Prot=03 Driver=option
I:  If#= 3 Alt= 0 #EPs= 1 Cls=ff(vend.) Sub=01 Prot=09 Driver=cdc_wdm
I:  If#= 4 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=01 Prot=08 Driver=qmi_wwan
I:  If#= 5 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=usb-storage
I:  If#= 6 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=usb-storage

* 3.7.1:
KERNEL[61750.414019] add
/devices/pci0000:00/0000:00:1d.7/usb2/2-6/2-6:1.3/usbmisc/cdc-wdm0
(usbmisc)
KERNEL[61750.414019] add
/devices/pci0000:00/0000:00:1d.7/usb2/2-6/2-6:1.3/usbmisc/cdc-wdm0
(usbmisc)

T:  Bus=02 Lev=01 Prnt=01 Port=05 Cnt=01 Dev#=  6 Spd=480 MxCh= 0
D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
P:  Vendor=12d1 ProdID=150a Rev=00.00
S:  Manufacturer=Huawei Technologies
S:  Product=HUAWEI Mobile
S:  SerialNumber=1234567890ABCDEF
C:  #Ifs= 7 Cfg#= 1 Atr=c0 MxPwr=500mA
I:  If#= 0 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=01 Prot=01 Driver=option
I:  If#= 1 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=01 Prot=02 Driver=option
I:  If#= 2 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=01 Prot=03 Driver=option
I:  If#= 3 Alt= 0 #EPs= 1 Cls=ff(vend.) Sub=01 Prot=09 Driver=qmi_wwan
I:  If#= 4 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=01 Prot=08 Driver=qmi_wwan
I:  If#= 5 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=usb-storage
I:  If#= 6 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50 Driver=usb-storage

Thanks,
Cedric

Re: qmi_wwan on Huawei E398

[Bjørn Mork]

Cedric Jehasse <cedric.jehasse@gmail.com> wrote:

>Hi,
>
>I'm trying to use qmi on an Huawei E398 dongle with ofono on a 3.7.1
>kernel. (this works with a 3.5.0 kernel)
>ofono looks for the class/subclass/protocol of the parent
>usb_interface device for the qmi_wwan and cdc_wdm devices. This must
>match with ff/01/08 and ff/01/09 Cls/Sub/Prot.
>
>Below is a trace of the udev events and usb-device output for a 3.5.0
>and 3.7.1 kernel. The difference is in the parent devices for wwan0
>and cdc-wdm0.
>The parent device for wwan0 is on a 3.7.1 kernel is If3. Is this
>normal?
>
>* 3.5.0:
>KERNEL[201.262240] add
>/devices/pci0000:00/0000:00:1d.7/usb2/2-6/2-6:1.3/usb/cdc-wdm0 (usb)
>KERNEL[201.347292] add
>/devices/pci0000:00/0000:00:1d.7/usb2/2-6/2-6:1.4/net/wwan0 (net)
>
>T:  Bus=02 Lev=01 Prnt=01 Port=05 Cnt=01 Dev#=  4 Spd=480 MxCh= 0
>D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
>P:  Vendor=12d1 ProdID=150a Rev=00.00
>S:  Manufacturer=Huawei Technologies
>S:  Product=HUAWEI Mobile
>S:  SerialNumber=1234567890ABCDEF
>C:  #Ifs= 7 Cfg#= 1 Atr=c0 MxPwr=500mA
>I:  If#= 0 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=01 Prot=01 Driver=option
>I:  If#= 1 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=01 Prot=02 Driver=option
>I:  If#= 2 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=01 Prot=03 Driver=option
>I:  If#= 3 Alt= 0 #EPs= 1 Cls=ff(vend.) Sub=01 Prot=09 Driver=cdc_wdm
>I:  If#= 4 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=01 Prot=08 Driver=qmi_wwan
>I:  If#= 5 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50
>Driver=usb-storage
>I:  If#= 6 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50
>Driver=usb-storage
>
>* 3.7.1:
>KERNEL[61750.414019] add
>/devices/pci0000:00/0000:00:1d.7/usb2/2-6/2-6:1.3/usbmisc/cdc-wdm0
>(usbmisc)
>KERNEL[61750.414019] add
>/devices/pci0000:00/0000:00:1d.7/usb2/2-6/2-6:1.3/usbmisc/cdc-wdm0
>(usbmisc)
>
>T:  Bus=02 Lev=01 Prnt=01 Port=05 Cnt=01 Dev#=  6 Spd=480 MxCh= 0
>D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1
>P:  Vendor=12d1 ProdID=150a Rev=00.00
>S:  Manufacturer=Huawei Technologies
>S:  Product=HUAWEI Mobile
>S:  SerialNumber=1234567890ABCDEF
>C:  #Ifs= 7 Cfg#= 1 Atr=c0 MxPwr=500mA
>I:  If#= 0 Alt= 0 #EPs= 3 Cls=ff(vend.) Sub=01 Prot=01 Driver=option
>I:  If#= 1 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=01 Prot=02 Driver=option
>I:  If#= 2 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=01 Prot=03 Driver=option
>I:  If#= 3 Alt= 0 #EPs= 1 Cls=ff(vend.) Sub=01 Prot=09 Driver=qmi_wwan
>I:  If#= 4 Alt= 0 #EPs= 2 Cls=ff(vend.) Sub=01 Prot=08 Driver=qmi_wwan
>I:  If#= 5 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50
>Driver=usb-storage
>I:  If#= 6 Alt= 0 #EPs= 2 Cls=08(stor.) Sub=06 Prot=50
>Driver=usb-storage
>
>Thanks,
>Cedric

This looks right to me. There is a single function using two USB interfaces. We started out letting the cdc-wdm driver handle the control interface and the qmi_wwan driver the data interface. This is what you see in 3.5. But splitting a function like this was very awkward and made devices like the E398 behave differently from most other QMI devices, which only use a single USB interface. 

So we changed this to let the qmi_wwan driver handle both interfaces. This is what you see in 3.7. The control interface is now the parent of both the cdc_wdm character device and the wwan network device and the data interface is just a data interface.

I realize that this is balancing on the edge of acceptable userspace visible changes, but all this did was making devices like the E398 look similar to single interface devices. Which already had to be supported by the userspace applications.

Now I understand that ofono does a lot stricter matching than I have anticipated, looking at the vendor specific subclass and protocol fields of the wwan parent interface. I don't think we can fix that without updating ofono. Sorry. If it is going to do that then it needs to accept both ff/01/08 and ff/01/09.


Bjørn

Re: qmi_wwan on Huawei E398

[Cedric Jehasse]

>
> Have you tried if the same happens with modemmanager?
>
No, i haven`t. And it's not really relevant for me, as modemmanager
might match interfaces in a different way.

It looked weird to me to have a single parent interface for both the
cdc_dwm device and the wwan device, while there are separate
usb_interfaces for control and data.
From Bjørn's explanation, i understand why this was done. And i will
take a look at how this can be changed in ofono.

Thanks,
Cedric