Date:	Fri, 14 Nov 2014 10:18:00 -0600
From:	Dan Williams <dcbw@...hat.com>
To:	sedat.dilek@...il.com
Cc:	Greg KH <greg@...ah.com>, "David S. Miller" <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	linux-usb@...r.kernel.org,
	Aleksander Morgado <aleksander@...ksander.es>
Subject: Re: Understanding what's going on when using a Huawei E173 USB 3G
 web-stick (UMTS/HSPA)

On Fri, 2014-11-14 at 11:56 +0100, Sedat Dilek wrote:
> On Wed, Nov 12, 2014 at 2:21 PM, Sedat Dilek <sedat.dilek@...il.com> wrote:
> > On Tue, Nov 4, 2014 at 5:55 PM, Dan Williams <dcbw@...hat.com> wrote:
> >> On Tue, 2014-11-04 at 16:11 +0100, Sedat Dilek wrote:
> >>> Hi,
> >>>
> >>> I wanted to understand what is going on the kernel-side when
> >>> connecting to the Internet via a Huawei E173 USB web-stick (3rd
> >>> Generation: UMTS / HSPA).
> >>>
> >>> Especially the correlation between the diverse USB/NET kernel-drivers
> >>> and how the networking is setup.
> >>
> >
> > [ Sitting in front of a foreign Windows machine ]
> >
> > [ CC Aleksander ]
> >
> > Hi Dan,
> >
> > sorry for the late (and short) response.
> >
> > AFAICS you have given a "skeleton" for a "usb-wwan-networking"
> > documentation :-).
> >
> > Personally, I would like to take into account some kernel-config
> > options and some more things.
> >
> 
> I started with documenting...
> 
> I have still some difficulties in understanding USB WWAN Networking.
> So, this is what I revealed...
> 
> ##### USB: HUAWEI E173 3G/UMTS/HSPA INTERNET STICK
> 
> ### USB-NETWORKING AND WWAN SETUP
> CONFIG_USB_USBNET=m        <--- usb networking
> CONFIG_USB_NET_CDCETHER=m  <--- usb-wwan (net) configuration
> CONFIG_USB_SERIAL_WWAN=m   <--- usb-wwan (serial) configuration
> CONFIG_USB_SERIAL_OPTION=m <--- usb-serial driver called "option"

Most WWAN devices actually require option, because most WWAN devices
have "serial" ports (even if they aren't used for PPP), and 'option' is
the driver that handles this.  The 'option' name is historic, but the
driver should really be called something like 'wwan-serial-generic' or
something like that.

You're missing a few other "net" type drivers:

CONFIG_USB_NET_QMI_WWAN = Qualcomm QMI capable devices (net)
CONFIG_USB_HSO = "Option High-Speed" (net) devices
CONFIG_USB_NET_KALMIA = Samsung LTE dongle (net)
CONFIG_USB_SIERRA_NET = Sierra devices (net)
CONFIG_USB_NET_CDC_NCM = Ericsson F5321 (?) and some others (net)
CONFIG_USB_NET_HUAWEI_CDC_NCM = Huawei NCM variant (net)
CONFIG_USB_VL600 = LG VL600 / AD600 LTE device (net)
CONFIG_USB_NET_CDC_MBIM = MBIM (net) devices (popular currently)

and maybe even:

CONFIG_USB_CDC_PHONET = Nokia phones and USB sticks, not "net" but
proprietary protocol that handles both data/control channels

For the "serial" side:

CONFIG_USB_ACM = generic "serial" devices, many are *not* WWAN but many
WWAN devices use this class/driver
CONFIG_USB_SERIAL_QCAUX = Various Qualcomm-based devices' "auxiliary"
ports (DIAG, GPS, etc)
CONFIG_USB_SERIAL_QUALCOMM = Firmware loading and "auxiliary" ports on
various Qualcomm Gobi devices
CONFIG_USB_SERIAL_SIERRAWIRELESS = Older Sierra device serial ports for
PPP/control and "auxiliary" functions

WWAN devices basically mix & match these drivers depending on what
interfaces the firmware exposes.

For example, some Sierra devices may require both
CONFIG_USB_SERIAL_SIERRAWIRELESS and CONFIG_USB_SIERRA_NET.

Older Sierra devices may use only CONFIG_USB_SERIAL_SIERRAWIRELESS and
do not provide a 'net' port at all, but use only PPP.

Sierra devices based on Icera chips may use CONFIG_USB_ACM and either
CONFIG_USB_SIERRA_NET or CONFIG_USB_NET_CDCETHER.

Some Huawei devices may use CONFIG_USB_NET_CDCETHER and either
CONFIG_USB_SERIAL_OPTION or CONFIG_USB_ACM.

Other Huawei devices may use CONFIG_USB_NET_QMI_WWAN and
CONFIG_USB_SERIAL_OPTION.

Even other Huawei devices may be Qualcomm Gobi type and use
CONFIG_USB_NET_QMI_WWAN and CONFIG_USB_SERIAL_QUALCOMM.

So you see it really depends on exactly how the firmware is implemented.
But in general, devices still fall into the categories I originally
listed, and the drivers fall into specific categories too ("net",
"serial", "proprietary"), and devices mix & match drivers to achieve the
end result.

Dan

> ### PPP OPTIONS
> CONFIG_PPP=y
> CONFIG_PPP_BSDCOMP=m
> CONFIG_PPP_DEFLATE=m
> CONFIG_PPP_FILTER=y
> CONFIG_PPP_MULTILINK=y
> CONFIG_PPP_ASYNC=m
> 
> Beyond the PPP options, I wanted to understand what
> CONFIG_USB_NET_CDCETHER does and why I need it.
> Can someone help?




> Thanks.
> 
> - Sedat -
> 
> [1] http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/drivers/net/usb/Kconfig#n189
> 
> P.S.: cdc_ether Kconfig option and checking my logs
> 
> From [1]...
> ...
> config USB_NET_CDCETHER
> tristate "CDC Ethernet support (smart devices such as cable modems)"
> depends on USB_USBNET
> default y
> help
>  This option supports devices conforming to the Communication Device
>  Class (CDC) Ethernet Control Model, a specification that's easy to
>  implement in device firmware.  The CDC specifications are available
>  from <http://www.usb.org/>.
> 
>  CDC Ethernet is an implementation option for DOCSIS cable modems
>  that support USB connectivity, used for non-Microsoft USB hosts.
>  The Linux-USB CDC Ethernet Gadget driver is an open implementation.
>    This driver should work with at least the following devices:
> 
>    * Dell Wireless 5530 HSPA
>      * Ericsson PipeRider (all variants)
>    * Ericsson Mobile Broadband Module (all variants)
>      * Motorola (DM100 and SB4100)
>      * Broadcom Cable Modem (reference design)
>    * Toshiba (PCX1100U and F3507g/F3607gw)
>    * ...
> 
>  This driver creates an interface named "ethX", where X depends on
>  what other networking devices you have in use.  However, if the
>  IEEE 802 "local assignment" bit is set in the address, a "usbX"
>  name is used instead.
> ...
> 
> From my logs...
> 
> $ dmesg | egrep -i 'option|wwan|ppp|3-1.2|huawei|gsm|modem'
> [    0.000000] please try 'cgroup_disable=memory' option if you don't
> want memory cgroups
> [    0.549498] PPP generic driver version 2.4.2
> [    1.299059] usb 3-1.2: new high-speed USB device number 3 using ehci-pci
> [    1.394084] usb 3-1.2: New USB device found, idVendor=12d1, idProduct=1436
> [    1.394095] usb 3-1.2: New USB device strings: Mfr=4, Product=3,
> SerialNumber=0
> [    1.394100] usb 3-1.2: Product: HUAWEI Mobile
> [    1.394103] usb 3-1.2: Manufacturer: HUAWEI Technology
> [    2.115424] usb-storage 3-1.2:1.0: USB Mass Storage device detected
> [    2.125026] usb-storage 3-1.2:1.1: USB Mass Storage device detected
> [    2.125607] usb-storage 3-1.2:1.2: USB Mass Storage device detected
> [    2.125888] usb-storage 3-1.2:1.3: USB Mass Storage device detected
> [    2.126187] usb-storage 3-1.2:1.4: USB Mass Storage device detected
> [    2.126461] usb-storage 3-1.2:1.5: USB Mass Storage device detected
> [    2.127098] scsi host11: usb-storage 3-1.2:1.5
> [    2.129370] usb-storage 3-1.2:1.6: USB Mass Storage device detected
> [    2.131685] scsi host12: usb-storage 3-1.2:1.6
> [    3.127317] scsi 11:0:0:0: CD-ROM            HUAWEI   Mass Storage
>    2.31 PQ: 0 ANSI: 2
> [    3.137589] scsi 12:0:0:0: Direct-Access     HUAWEI   SD Storage
>    2.31 PQ: 0 ANSI: 2
> [   13.500302] cdc_ether 3-1.2:1.1 wwan0: register 'cdc_ether' at
> usb-0000:00:1a.0-1.2, Mobile Broadband Network Device,
> 02:50:f3:00:00:00
> [   14.160221] usbcore: registered new interface driver option
> [   14.160820] usbserial: USB Serial support registered for GSM modem (1-port)
> [   14.160940] option 3-1.2:1.0: GSM modem (1-port) converter detected
> [   14.163032] usb 3-1.2: GSM modem (1-port) converter now attached to ttyUSB0
> [   14.163305] option 3-1.2:1.3: GSM modem (1-port) converter detected
> [   14.163676] usb 3-1.2: GSM modem (1-port) converter now attached to ttyUSB1
> [   14.163742] option 3-1.2:1.4: GSM modem (1-port) converter detected
> [   14.165227] usb 3-1.2: GSM modem (1-port) converter now attached to ttyUSB2
> [   72.877065] PPP BSD Compression module registered
> [   72.881701] PPP Deflate Compression module registered
> - EOT -
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