Re: cdc_ether.c incompatible with Nokia 6110 Navigator: Where's the problem?

> Date: Thu, 18 Oct 2007 13:48:33 +0200
> From: Hadmut Danisch <[email protected]>
>
> Hi,
>
> I just replaced an older Sony Ericsson mobile with a Nokia 6110
> Navigator and expected it to work in the same way: plug into USB and
> have a usb0 ethernet device.

Why ... is that how it's documented to work with Linux?


>	But there's a problem:
>
>
> When I plug the mobile in, the kernel reports 
>
>   bad CDC descriptors
>
>
> I have tracked this down to cdc_ether.c , in the clause
>
> 		case USB_CDC_ACM_TYPE:
> 			/* paranoia:  disambiguate a "real" vendor-specific
> 			 * modem interface from an RNDIS non-modem.
> 			 */
> 			if (rndis) {
> 				struct usb_cdc_acm_descriptor *acm;
>
> 				acm = (void *) buf;
> 				if (acm->bmCapabilities) {
> 					dev_dbg(&intf->dev,
> 						"ACM capabilities %02x, "
> 						"not really RNDIS?\n",
> 						acm->bmCapabilities);
> 					goto bad_desc;
> 				}
> 			}
> 			break;
>
>
> which prints 
>
>   rndis_host 1-3.1:1.10: ACM capabilities 0f, not really RNDIS?

That seems appropriate.  The descriptors you show later indicate
that it's not really RNDIS.


> I am not at all familiar with USB programming, but for some reason the 
> cdc_ether.c expects the bmCapabilities to be zero when an rndis
> devices is found. 

That's because Microsoft specified that, as I recall.  Of course,
they've played (undocumented) games with more recent versions of
their RNDIS crap.  But they haven't AFAIK gone so far as to let
this interface fit.


> When I remove the 'goto bad_desc', it continues with a SubType 6 
> (Union Functional Descriptor) entry and then issues the error message
>
> rndis_host 1-3.1:1.10: RNDIS init failed, -32

That is, it's neither looks nor acts like RNDIS.
This diagnostic means that it doesn't even respond
to the funky RPC protocol RNDIS devices implement.


> As I said, I am not familiar with USB protocols and programming, but
> even the output of lsusb -v reports problems (invalid and unrecognized
> CDC) with the descriptor: 

Right, there are some standard interfaces here and many nonstandard
ones.


> Bus 001 Device 007: ID 0421:046e Nokia Mobile Phones 
> Device Descriptor:
>   bLength                18
>   bDescriptorType         1
>   bcdUSB               2.00
>   bDeviceClass            2 Communications
>   bDeviceSubClass         0 
>   bDeviceProtocol         0 
>   bMaxPacketSize0        64
>   idVendor           0x0421 Nokia Mobile Phones
>   idProduct          0x046e 
>   bcdDevice            1.00
>   iManufacturer           1 Nokia
>   iProduct                2 Nokia 6110 Navigator
>   iSerial                 0 
>   bNumConfigurations      1
>   Configuration Descriptor:
>     bLength                 9
>     bDescriptorType         2
>     wTotalLength          408
>     bNumInterfaces         14
>     bConfigurationValue     1
>     iConfiguration          4 Bulk transfer method configuration
>     bmAttributes         0xc0
>       Self Powered
>     MaxPower               20mA
>     Interface Descriptor:
>       bLength                 9
>       bDescriptorType         4
>       bInterfaceNumber        0
>       bAlternateSetting       0
>       bNumEndpoints           0
>       bInterfaceClass         2 Communications
>       bInterfaceSubClass      8 Wireless Handset Control

Basically means:  "this is complicated USB stuff".  ;)


>       bInterfaceProtocol      0 
>       iInterface              0 
>       CDC Header:
>         bcdCDC               1.10
>       CDC WHCM:
>         bcdVersion           1.00
>       CDC Union:
>         bMasterInterface        0
>         bSlaveInterface         1 2 3 4 5 6 7 8 9 10 11 12 13 

I didn't think Union descriptors were supposed to be used this way,
but maybe they are...


>     Interface Descriptor:
>       bLength                 9
>       bDescriptorType         4
>       bInterfaceNumber        1
>       bAlternateSetting       0
>       bNumEndpoints           0
>       bInterfaceClass         2 Communications
>       bInterfaceSubClass      8 Wireless Handset Control
>       bInterfaceProtocol      1 
>       iInterface              0 
>       CDC Header:
>         bcdCDC               1.10
>       INVALID CDC (Telephone Operations):  05 24 08 00 01

Telephone operations descriptors are only four bytes long,
not five; that's why this descriptor is invalid.

>       CDC Union:
>         bMasterInterface        1
>         bSlaveInterface         2 3 
>     Interface Descriptor:
>       bLength                 9
>       bDescriptorType         4
>       bInterfaceNumber        2
>       bAlternateSetting       0
>       bNumEndpoints           0
>       bInterfaceClass         2 Communications
>       bInterfaceSubClass    254 

The current www.usb.org website doesn't seem to have documents
defining this interface subclass (0xfe).

>       bInterfaceProtocol      0 
>       iInterface              0 
>       CDC Header:
>         bcdCDC               1.10
>       UNRECOGNIZED CDC:  05 24 ab 05 15

Ditto this descriptor type (0xab).

>       CDC Union:
>         bMasterInterface        2
>         bSlaveInterface         3 

Curious ... note the odd master/slave interface structure:

	0 	masters 1 2 3 4 5 6 7 8 9 10 11 12 13 
	1	masters 2 3
	2	masters 3
	(etc)

So interface 3 has three different masters ... right, sure it does.


>     Interface Descriptor:
>       bLength                 9
>       bDescriptorType         4
>       bInterfaceNumber        3
>       bAlternateSetting       0
>       bNumEndpoints           0
>       bInterfaceClass        10 CDC Data
>       bInterfaceSubClass      0 Unused
>       bInterfaceProtocol      0 
>       iInterface              0 

Presumably there's a reason to have an altsetting for this interface.

>     Interface Descriptor:
>       bLength                 9
>       bDescriptorType         4
>       bInterfaceNumber        3
>       bAlternateSetting       1
>       bNumEndpoints           2
>       bInterfaceClass        10 CDC Data
>       bInterfaceSubClass      0 Unused
>       bInterfaceProtocol      0 
>       iInterface              0 
>       Class specific interface descriptor for class 10 is unsupported

Unsupported, because it's not supposed to have descriptors.  Of course,
"lsusb" should have dumped that raw data; that's a minor bug to fix.

>       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     0x84  EP 4 IN
>         bmAttributes            2
>           Transfer Type            Bulk
>           Synch Type               None
>           Usage Type               Data
>         wMaxPacketSize     0x0040  1x 64 bytes
>         bInterval               0

(End first chunk of confusion)


>     Interface Descriptor:
>       bLength                 9
>       bDescriptorType         4
>       bInterfaceNumber        4
>       bAlternateSetting       0
>       bNumEndpoints           0
>       bInterfaceClass         2 Communications
>       bInterfaceSubClass     11 OBEX
>       bInterfaceProtocol      0 
>       iInterface              6 SYNCML-SYNC
>       CDC Header:
>         bcdCDC               1.10
>       CDC OBEX:
>         bcdVersion           1.00
>       CDC Union:
>         bMasterInterface        4
>         bSlaveInterface         5 
>     Interface Descriptor:
>       bLength                 9
>       bDescriptorType         4
>       bInterfaceNumber        5
>       bAlternateSetting       0
>       bNumEndpoints           0
>       bInterfaceClass        10 CDC Data
>       bInterfaceSubClass      0 Unused
>       bInterfaceProtocol      0 
>       iInterface              0 
>     Interface Descriptor:
>       bLength                 9
>       bDescriptorType         4
>       bInterfaceNumber        5
>       bAlternateSetting       1
>       bNumEndpoints           2
>       bInterfaceClass        10 CDC Data
>       bInterfaceSubClass      0 Unused
>       bInterfaceProtocol      0 
>       iInterface              0 
>       Endpoint Descriptor:
>         bLength                 7
>         bDescriptorType         5
>         bEndpointAddress     0x85  EP 5 IN
>         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     0x02  EP 2 OUT
>         bmAttributes            2
>           Transfer Type            Bulk
>           Synch Type               None
>           Usage Type               Data
>         wMaxPacketSize     0x0040  1x 64 bytes
>         bInterval               0

OK, that's OBEX ... ISTR there are some userspace Linux tools that
can handle that.


>     Interface Descriptor:
>       bLength                 9
>       bDescriptorType         4
>       bInterfaceNumber        6
>       bAlternateSetting       0
>       bNumEndpoints           0
>       bInterfaceClass         2 Communications
>       bInterfaceSubClass     11 OBEX
>       bInterfaceProtocol      0 
>       iInterface              7 PC Suite Services
>       CDC Header:
>         bcdCDC               1.10
>       CDC OBEX:
>         bcdVersion           1.00
>       CDC Union:
>         bMasterInterface        6
>         bSlaveInterface         7 
>     Interface Descriptor:
>       bLength                 9
>       bDescriptorType         4
>       bInterfaceNumber        7
>       bAlternateSetting       0
>       bNumEndpoints           0
>       bInterfaceClass        10 CDC Data
>       bInterfaceSubClass      0 Unused
>       bInterfaceProtocol      0 
>       iInterface              0 
>     Interface Descriptor:
>       bLength                 9
>       bDescriptorType         4
>       bInterfaceNumber        7
>       bAlternateSetting       1
>       bNumEndpoints           2
>       bInterfaceClass        10 CDC Data
>       bInterfaceSubClass      0 Unused
>       bInterfaceProtocol      0 
>       iInterface              0 
>       Endpoint Descriptor:
>         bLength                 7
>         bDescriptorType         5
>         bEndpointAddress     0x86  EP 6 IN
>         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     0x03  EP 3 OUT
>         bmAttributes            2
>           Transfer Type            Bulk
>           Synch Type               None
>           Usage Type               Data
>         wMaxPacketSize     0x0040  1x 64 bytes
>         bInterval               0

A second OBEX interface.  I don't know if those userspace tools
will handle both of these, but I'd hope they would.


>     Interface Descriptor:
>       bLength                 9
>       bDescriptorType         4
>       bInterfaceNumber        8
>       bAlternateSetting       0
>       bNumEndpoints           1
>       bInterfaceClass         2 Communications
>       bInterfaceSubClass      2 Abstract (modem)
>       bInterfaceProtocol      1 AT-commands (v.25ter)
>       iInterface              8 CDC Comms Interface
>       CDC Header:
>         bcdCDC               1.00
>       CDC ACM:
>         bmCapabilities       0x0f
>           connection notifications
>           sends break
>           line coding and serial state
>           get/set/clear comm features
>       CDC Union:
>         bMasterInterface        8
>         bSlaveInterface         9 
>       Endpoint Descriptor:
>         bLength                 7
>         bDescriptorType         5
>         bEndpointAddress     0x81  EP 1 IN
>         bmAttributes            3
>           Transfer Type            Interrupt
>           Synch Type               None
>           Usage Type               Data
>         wMaxPacketSize     0x0040  1x 64 bytes
>         bInterval             128
>     Interface Descriptor:
>       bLength                 9
>       bDescriptorType         4
>       bInterfaceNumber        9
>       bAlternateSetting       0
>       bNumEndpoints           2
>       bInterfaceClass        10 CDC Data
>       bInterfaceSubClass      0 Unused
>       bInterfaceProtocol      0 
>       iInterface              9 CDC Data Interface
>       Endpoint Descriptor:
>         bLength                 7
>         bDescriptorType         5
>         bEndpointAddress     0x87  EP 7 IN
>         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     0x04  EP 4 OUT
>         bmAttributes            2
>           Transfer Type            Bulk
>           Synch Type               None
>           Usage Type               Data
>         wMaxPacketSize     0x0040  1x 64 bytes
>         bInterval               0

That looks like a fairly generic CDC-ACM interface ... and it
says that it accepts v.25ter style AT-commands, so it "should"
be a real modem device.  (A followup note from you reported that
you had PPP working over that link...)


>     Interface Descriptor:
>       bLength                 9
>       bDescriptorType         4
>       bInterfaceNumber       10
>       bAlternateSetting       0
>       bNumEndpoints           1
>       bInterfaceClass         2 Communications
>       bInterfaceSubClass      2 Abstract (modem)
>       bInterfaceProtocol    255 Vendor Specific (MSFT RNDIS?)
>       iInterface             10 CDC Comms Interface
>       CDC Header:
>         bcdCDC               1.00
>       CDC ACM:
>         bmCapabilities       0x0f
>           connection notifications
>           sends break
>           line coding and serial state
>           get/set/clear comm features

To be true RNDIS this should have capabilities "0x00".
It should also include a CDC "Call Management" descriptor.

>       CDC Union:
>         bMasterInterface        10
>         bSlaveInterface         11 
>       Endpoint Descriptor:
>         bLength                 7
>         bDescriptorType         5
>         bEndpointAddress     0x82  EP 2 IN
>         bmAttributes            3
>           Transfer Type            Interrupt
>           Synch Type               None
>           Usage Type               Data
>         wMaxPacketSize     0x0040  1x 64 bytes
>         bInterval             128
>     Interface Descriptor:
>       bLength                 9
>       bDescriptorType         4
>       bInterfaceNumber       11
>       bAlternateSetting       0
>       bNumEndpoints           2
>       bInterfaceClass        10 CDC Data
>       bInterfaceSubClass      0 Unused
>       bInterfaceProtocol      0 
>       iInterface             11 CDC Data Interface
>       Endpoint Descriptor:
>         bLength                 7
>         bDescriptorType         5
>         bEndpointAddress     0x88  EP 8 IN
>         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     0x05  EP 5 OUT
>         bmAttributes            2
>           Transfer Type            Bulk
>           Synch Type               None
>           Usage Type               Data
>         wMaxPacketSize     0x0040  1x 64 bytes
>         bInterval               0

I could imagine that being a real RNDIS interface ... except for
those two contrary-to-spec descriptors, and the fact that you
showed (above) that it doesn't respond to the funky RPC calls
that any real RNDIS device will handle.

Clearly this is not RNDIS; it's yet another proprietary
interface to this phone.  (And obviously, it's not CDC-Ether;
I don't know why you even bothered trying that.)


>     Interface Descriptor:
>       bLength                 9
>       bDescriptorType         4
>       bInterfaceNumber       12
>       bAlternateSetting       0
>       bNumEndpoints           0
>       bInterfaceClass         2 Communications
>       bInterfaceSubClass    253 

Another subclass code not defined by current USB.org specs...

>       bInterfaceProtocol      0 
>       iInterface             12 LCIF_Alt0
>       CDC Header:
>         bcdCDC               1.10
>       UNRECOGNIZED CDC:  05 24 fc 00 01

... another descriptor type (0xfc) not defined by USB.org ...

>       CDC Union:
>         bMasterInterface        12
>         bSlaveInterface         13 
>       UNRECOGNIZED CDC:  04 24 fd 00

... another descriptor type (0xfd) not defined by USB.org ...

>     Interface Descriptor:
>       bLength                 9
>       bDescriptorType         4
>       bInterfaceNumber       13
>       bAlternateSetting       0
>       bNumEndpoints           0
>       bInterfaceClass        10 CDC Data
>       bInterfaceSubClass      0 Unused
>       bInterfaceProtocol      0 
>       iInterface              0 
>     Interface Descriptor:
>       bLength                 9
>       bDescriptorType         4
>       bInterfaceNumber       13
>       bAlternateSetting       1
>       bNumEndpoints           2
>       bInterfaceClass        10 CDC Data
>       bInterfaceSubClass      0 Unused
>       bInterfaceProtocol      0 
>       iInterface              0 
>       Endpoint Descriptor:
>         bLength                 7
>         bDescriptorType         5
>         bEndpointAddress     0x83  EP 3 IN
>         bmAttributes            3
>           Transfer Type            Interrupt
>           Synch Type               None
>           Usage Type               Data
>         wMaxPacketSize     0x0040  1x 64 bytes
>         bInterval              32
>       Endpoint Descriptor:
>         bLength                 7
>         bDescriptorType         5
>         bEndpointAddress     0x06  EP 6 OUT
>         bmAttributes            2
>           Transfer Type            Bulk
>           Synch Type               None
>           Usage Type               Data
>         wMaxPacketSize     0x0040  1x 64 bytes
>         bInterval              32

End of mysterious LCIF_Alt0 interface.


> Device Status:     0x0001
>   Self Powered
>

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