Friday, January 25, 2008

Fingerprint reader on 6910p

I tried to make the fingerprint reader on the 6910p to work. Surprisingly it works alright. I grabbed the packages and instruction from here.

I then run fprint_demo and registered by right index finger. So far its alright, its not perfect. There are shortcoming (mostly not the fault of fprint) like what is pointed at this thread.

Tuesday, January 15, 2008

Little tweak here and there

I am unfortunate that I own a hard disk (Hitachi HTS722012K9SA00) that had a too aggressive power management. See for details.

I tried different settings of "hdparm -B" and have observed the following:

127 - spins down and parks the head
128 to 191 - parks the head
192 to 255 - never parks the head

I have also observed that when the 6910p is on battery it does not keep on unparking the head. It seems that the best settings in battery is the default 128. I am now using 128 as the apm value when on battery. I have also added a script "/etc/acpi/resume.d/" as it seems "/etc/acpi/" will set never call "hdparm -B" as the power has never changed state when the laptop resumes. My contains the following:


. /etc/default/acpi-support
. /usr/share/acpi-support/power-funcs

for x in /proc/acpi/ac_adapter/*; do
grep -q off-line $x/state

if [ $? = 0 ] && [ x$1 != xstop ]; then
if [ x$ENABLE_LAPTOP_MODE = xtrue ]; then
$HDPARM -S $SPINDOWN_TIME /dev/sda 2>/dev/null
$HDPARM -B 128 /dev/sda 2>/dev/null
if [ x$ENABLE_LAPTOP_MODE = xtrue ]; then
$HDPARM -S 0 /dev/sda 2>/dev/null
$HDPARM -B 254 /dev/sda 2>/dev/null

For the past 2 days my 6910p wireless seems to be disconnecting. I am not sure if my wireless is getting interference from another AP or not, as this has happened to my other laptops before. I haven't seen this problem from the 6910p for a few weeks or my old nx8220. I have also changed my WRT54G firmware from thibor to tomato firmware for the past few days. Maybe the tomato firmware is causing the problem, but I doubt it so I decided to upgrade my iwlwifi from 1.2.22 to 1.2.23 and mac80211 from 10.0.2 to 10.0.4. So far it looks alright after several hours of use. I have to wait a few more hours, as it it happened for the past few days near midnight... maybe there is something happening to the 2.4ghz rf during that time in our neighborhood.

I am also trying to look at my power draw with the help of powertop from intel. Not sure how much I can save with the tweaks... still playing with it.

Friday, January 4, 2008

xrandr and radeonhd crtc problem

I have been having a problem with my 6910p re-enabling the DVI or VGA external output. It does work when I re-login or restart X, but after I disconnect the external monitor for a long time I couldn't enable it back. Here is what is happening to me:
xrandr --output DVI-D_1 --auto --right-of PANEL
X Error of failed request: BadMatch (invalid parameter attributes)
Major opcode of failed request: 154 (RANDR)
Minor opcode of failed request: 21 ()
Serial number of failed request: 19
Current serial number in output stream: 19
To resolve the issue I have to explicitly pass in the crtc number
xrandr --output DVI-D_1 --crtc 1 --auto --right-of PANEL
For a more detailed discussion of the problem you can look at xorg mailing list archive post here:

A newer xrandr should resolve the issue in the future, for now I just use --crtc switch.