netdev - Re: [PATCH net-next v6 0/3] The huawei_cdc

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Date:	Fri, 14 Mar 2014 16:25:59 +0200
From:	Pasi Kärkkäinen <pasik@....fi>
To:	Bjørn Mork <bjorn@...k.no>
Cc:	Dan Williams <dcbw@...hat.com>, netdev@...r.kernel.org,
	linux-usb@...r.kernel.org, Enrico Mioso <mrkiko.rs@...il.com>,
	Oliver Neukum <oliver@...kum.org>
Subject: Re: [PATCH net-next v6 0/3] The huawei_cdc_ncm driver / E3276
 problem

On Fri, Mar 14, 2014 at 02:33:36PM +0100, Bjørn Mork wrote:
> Pasi Kärkkäinen <pasik@....fi> writes:
> > On Fri, Mar 14, 2014 at 10:24:51AM +0100, Bjørn Mork wrote:
> >> Pasi Kärkkäinen <pasik@....fi> writes:
> >> 
> >> > # ifconfig wwp0s26u1u5i1
> >> > wwp0s26u1u5i1: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
> >> >         inet 10.8.219.204  netmask 255.255.255.248  broadcast 10.8.219.207
> >> >         inet6 fe80::e5b:8fff:fe27:9a64  prefixlen 64  scopeid 0x20<link>
> >> >         ether 0c:5b:8f:27:9a:64  txqueuelen 1000  (Ethernet)
> >> >         RX packets 0  bytes 0 (0.0 B)
> >> >         RX errors 1493  dropped 0  overruns 0  frame 0
> >> >
> >> > Note the RX errors.. ? 
> >> 
> >> 
> >> Yes, that is not expected and is quite possibly hiding the explanation.
> >> 
> >
> > Ok, good to know.
> >
> >> Could you do a usbmon dump to try to capture the contents of the USB
> >> buffers we drop here?  See
> >> https://www.kernel.org/doc/Documentation/usb/usbmon.txt
> >> 
> >> Note that the text interface may truncate the buffers too early for the
> >> result to be useful.  wireshark/thsark will for example allow you to
> >> capture the whole buffer (when snooping on the "usbmonX" interface - not
> >> the netdev!)
> >> 
> >
> > I'll try that.. 
> >
> >> We also have a few debug messages in the driver for different types of
> >> errors we drop.  Turning on those might explain something (assuming you
> >> have DYNAMIC_DEBUG enabled):
> >> 
> >>   ethtool -s wwp0s26u1u5i1 msglvl rx_err on
> >> 
> >> Note that these will be logged at "debug" level, so you need to turn on
> >> logging/showing such messages as well.
> >> 
> >
> > # uname -a
> > Linux localhost.localdomain 3.13.6-200.fc20.x86_64 #1 SMP Fri Mar 7 17:02:28 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
> >
> > # grep -i DYNAMIC_DEBUG /boot/config-3.13.6-200.fc20.x86_64
> > CONFIG_DYNAMIC_DEBUG=y
> >
> > # echo 8 > /proc/sys/kernel/printk
> > # cat /proc/sys/kernel/printk
> > 8       4       1       7
> >
> > # ethtool -s wwp0s26u1u5i1 msglvl rx_err on
> >
> > Is that enough?
> 
> I believe so, but I don't feel too steady on all the dynamic-ness here.
> 
> > I don't see any errors logged in "dmesg" output,
> > but the RX errors counters do keep increasing in ifconfig output.. 
> 
> OK, let's see if we can figure it out based on the usbmon data.
> 

http://pasik.reaktio.net/huawei-e3276-usbmon3.pcapng

(I did move the dongle to a different usb bus nr 3 to make it the only device on that bus before capturing..) 

So what I did:

- Start wireshark capture on USB bus nr 3.
- Plug in the Huawei E3276 dongle.
- Wait for usb_modeswitch to happen.
- Use minicom to talk to /dev/cdc-wdm0 and send AT commands to connect to Internet:
	- ATQ0 V1 E1 S0=0
	- AT^NDISDUP=1,1,"internet"

- After the dongle has connected query for DHCP status:
	- AT^DHCP?

- Launch dhcp client (dhclient) on wwp0s20u1i1 interface.
- Wait for a while and see RX error counters increasing on ifconfig output.
- Cancel (ctrl+c) the dhclient.
- Stop wireshark capture. 


Does that capture file show anything interesting to you? 

> 
> 
> Bjørn


Thanks,

-- Pasi

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