Julius Plenz – Blog

I've been toying around with the UMTS module in my X220 lately. I got a pre-paid SIM from blau.de, who offer 24h UMTS flatrates for 2,40 EUR. (This is probably my use case: Being somewhere without internet access for a day or two. This only happens so often, so I don't want a "real" flat.)

My UMTS card is manufactured by Sony Ericsson and connected via internal USB:

$ lsusb -v -s 004:003
    ...
    idVendor           0x0bdb Ericsson Business Mobile Networks BV
    idProduct          0x1911

The installation is easy: Just insert the SIM card behind the battery as shown here. Add yourself to the dialout group, log in again, and you're set.

You can first connect to your device using chat or picocom (which you can be terminated via C-a C-x). To ask if you can use the SIM without PIN, send the AT+CPIN? command:

$ picocom /dev/ttyACM0
...
AT+CPIN?
+CPIN: READY

If you're not ready to go, I would disable the PIN request using a regular phone. (I did.)

Dialling out is easy. I set up two profiles in the /etc/wvdial.conf that allow me to switch between "pay per megabyte" and "dayflat":

[Dialer blau]
Modem = /dev/ttyACM0
Init1 = AT+CGDCONT=1,"IP","internet.eplus.de"
Stupid mode = 1
phone= *99#
Username = blau
Password = blau

[Dialer tagesflat]
Modem = /dev/ttyACM0
Init1 = AT+CGDCONT=1,"IP","tagesflat.eplus.de"
Stupid mode = 1
phone= *99#
Username = blau
Password = blau

The rest happens automatically, once you invoke wvdial blau or wvdial tagesflat. (Note you have to execute these with root privileges because they want to modify pppd-related config files.) Most probably you want the follow-up command route add default dev ppp0 to route all traffic via the ppp0 interface.

In a test run I got a downstream speed of 190KB/s (city perimeter). Working over SSH is not painful at all.

I also played around with gammu a little bit.

$ gammu --identify
Device               : /dev/ttyACM0
Manufacturer         : Lenovo
Model                : unknown (F5521gw)
Firmware             : R2A07

The Wammu interface is nice, it can even receive SMS. But sending SMSes failed so far:

$ echo "Das ist ein Test" | gammu --debug textall --debug-file /tmp/gammu \
    sendsms TEXT +491785542342
...
1 "AT+CMGS=28"
2 "> 079194710716000011000C919471584532240000FF10C4F01C949ED341E5B41B442DCFE9^Z"
3 "+CMS ERROR: 500"

... which is somewhat of an "generic error". Maybe sending SMS is not supported at all. I'll look into that later.

Also, I'll have a look whether my Card supports GPS information retrieval. Thinkwiki claims a similar model does this. Interesting.

Update: Actually, I forgot one thing. I keep the following two entries in my /etc/wvdial.conf:

[Dialer on]
Modem = /dev/ttyACM0
Init1 = AT+CFUN=1

[Dialer off]
Modem = /dev/ttyACM0
Init1 = AT+CFUN=4

The actual sequence is now: wvdial on && wvdial blau. The AT+CFUN=1 will active the radio equipment, which is necessary. And, suddenly, also SMS delivery works! :-)

I got a brand new Thinkpad X220 on thursday. I'm not much into hardware, I think it should mainly work. I have a model with 4 GB of RAM, an i7 at 2.7 GHz, UMTS preinstalled, SSD instead of a HDD and an IPS panel. It's a really nifty thing.

Paying the extra money for the SSD is totally worth it. Everything happens instantaneous. The bootup process is down to five seconds. The IPS panel is really worth it, too. ThinkPads have long been criticized for their bad displays – with the new panel at full brightness, my regular screen looks really dim and grey...

The Debian netinstall works smoothly. I haven't come around to testing all the stuff like the DisplayPort connectors, Bluetooth, UMTS, USB 3.0. But the usual stuff works out of the box.

However, there are major problems with the power management of both the graphics card and the whole system, the latter one being a regression in the recent 3.0 and 3.1 kernel series regarding ASPM. Currently I'm using the 3.1.0-1-amd64 kernel with the pcie_aspm=force boot parameter. I cannot really see a difference in power consumtion when varying this parameter, though.

A major thing, however, is re-enabling the RC6 mode of the graphics chip. This alone saves more than 4W when the computer is in an idle state. My /etc/modprobe.d/i915-kms.conf looks like this now:

options i915 modeset=1
options i915 i915_enable_rc6=1
options i915 i915_enable_fbc=1
options i915 lvds_downclock=1

Suspend/resume works fine, no flickering effects. I use the following command to find out the current power consumption:

while sleep 1; do
    awk '{printf"%.2f\n",$1/-1000}' < /sys/devices/platform/smapi/BAT0/power_now;
done

This requires the tp_smapi kernel module to be loaded. With full brightness (0) and while writing this blog article, the consumption is at ~12W; with medium brightness (8) it's ~8.5W; at the lowest brightness (15) it's ~8W; With the display completely turned off, it's ~6.5W. There are people who claim they only have an ~5.4 power consumption. If you have any other hints on this or if you own an X220 yourself, I'd be interested in the details.