Friday, July 6, 2018

USB 3.0 on Linux ( AMD processors )

You'll find at times that your USB 3 device is running on USB 2 speeds. This  can be addressed by passing a  kernel parameter in grub. "amd_iommu=on" 

The input–output memory management unit (IOMMU) is a memory management unit (MMU) that connects a direct-memory-access–capable (DMA-capable) I/O bus to the main memory.

To make the changes permanent, add the parameter to /etc/default/grub 


and run "sudo update-grub"

Remember that  the effective transfer rate will be dependent on internal disks and other possible bottlenecks . 

Saturday, June 30, 2018

TP-Link TL-WN725N wireless USB adapter on Linux

The default driver which is auto loaded by the kernel does not seem to work as expected . The workaround is simple. Go to the TP link site here :

download the driver , unzip the file and ,

$ apt-get install gcc

$ make clean
$ make


$sudo cp 88x2bu.ko /lib/modules/[kernel version]/kernel/drivers/net/wireless/ #[kernel
version] is the directory name of the system kernel version

$ sudo depmod  –a
$ sudo modprobe 88x2bu.ko

in my case it was 8188eu.ko

lsmod to check

Blacklist the existing module by adding  the line

blacklist   r8188eu

to  /etc/modprobe.d/blacklist.conf 

unplug the dongle and plug it back again .

Seems to work perfectly now! :) 

Monday, February 2, 2015

Flash plugin vulnerability warning in firefox 35.0.1

There seems to be some incompatibility between ubuntu and flash releases . I never liked flash player because it tuns very inefficiently on linux  but anyways if you have the vulnerability warning ,

do this :

1 ) Get the tar bundle from
2 ) tar -xvzf   install_flash_player_11_linux.i386.tar.gz
3 ) sudo cp  /usr/lib/mozilla/plugins/
4 ) Restart firefox

Its trivial and  irritating .. but this solves the problem..

Thursday, October 2, 2014

pulse audio clicking/popping sounds

After a recent routine update , my audio streams had clicks /pops in it which did not seem to occur  synchronously  . After some investigation I figured out that the problem was with pulseaudio  timer based scheduling . This parameter is driver specific and may be required "on" on some sound cards. 

To turn timer-based scheduling off add tsched=0 in /etc/pulse/
After editing the above file , restart pulse audio  sudo service pulseaudio restart
This fixed my clicks and pops but introduced another glitch which i'm working on right now. Alsamixer is reset every time I play mplayer .. aaarrgh !!!

UPDATE :  That fix was irritating . Pulse is probably broken since the latest update  . The best thing to do is use JACK :) . jack can coexist with pulse and is lighter , more efficient and works great .

start it by using  " jackd -d alsa -r 44100 "   and to make mplayer use jack , just use vo=jack :)

Problem solved

Saturday, June 28, 2014

Multiple displays with xrandr

Do you have a LCD TV or a spare monitor ? You can use that extra screen size  to see more code  : ) or watch a movie.  It's easy to manage multiple displays in linux using xrandr. Install xrandr if you havent already . I use a trivial script to switch between my displays . Here it is :

# switch from VGA to LVDS ( xrandr )

# set wall to the path of your wallpaper

if [[ $frm -eq 1 ]]
        xrandr --output VGA1 --auto
        sleep 2
        xrandr --output LVDS1 --off
        fbsetbg $wall  
        xrandr --output VGA1 --off
        sleep 1
        xrandr --output LVDS1 --auto
        fbsetbg $wall

use xrandr --query  to check which displays have been detected and change the names of the displays accordingly. Also , If you are using fluxbox then make sure that  it's compiled with xinerama support. It helps with the window geometries etc. when switching.  Use a keybinding in fluxbox to switch from  VGA (tv) and LVDS ( laptop) so that if there is a power cut , you wont have a switched off laptop screen ! .

Monday, March 24, 2014

Fixing the "Whiteout" for the samsung 21 inch TV

Samsung has a design flaw in their LCD TV's . The  flaw leads to something called a "whiteout" wherein the screen turns bright white and  nothing is displayed. The problem is a PCB situated on the top back of the panel . This PCB is covered by a metal cover with which it eventually shorts. Insulating The metal studs under the metal cover solves this issue! . Use insulating tape (electrical tape ) . Also Insulate under the PCB . Just in case .. Don't stick tape to PCB! .. just under PCB and over the metal studs touching the PCB .

JKturner has an excellent article on the same so I wont repeat the whole thing here . His  however is for the 32 '' TV. It's a good read for anyone attempting to solve the 21 inch but remember , on the 21, there is only one PCB at the top back of the panel (after you have removed the chassis housing the motherboard and SMPS).

An open TV chassis can be somewhat intimidating to some, so be brave but be gentle with the internal  connectors. BTW,  this became my first TV hack partly because I was too lazy to take it to the service center :P and partly because It appears that the service center folks misdiagnose it ( perhaps deliberately !) as a blown panel and charge the consumer for a new one ....  and the whole hack worked like a charm !! .

happy hacking

Monday, September 30, 2013

My Timex Ironman leaked!!

Had a nice dip in the Arabian sea and when I was  walking back to the shore I glanced at my trusty Ironman timex .. The screen was blank !!!. I couldn't  believe it . Back home I opened the back cover and discovered that the o-ring was slightly misaligned . I took one strap off , took the machine out of its casing , cleaned the inner casing , placed the machine back , aligned the o-ring , screwed the back cover on to the casing and attached the strap to the casing . 

You will need a precision kit ( small screwdrivers) to service this watch.

  • 1) take one strap off : carefully press the pin release with a screwdriver and slide the pin out of the groove. Gently pull the strap in one direction .
  • 2) Unscrew the metal cover
  • 3) Align the o-ring in it's groove and keep it aligned while closing the back cover
  • 4) close the back cover and tighten  alternate (opposite) screws . 
  • 5) make sure all screws are tightened properly
The battery can be easily replaced by unhooking the battery cover gently from its plastic hooks using a pin . The case once opened needs to be very carefully reassembled to avoid losing the water resist. Silicone sealant is recommended but I didn't have any  so I sealed it just by cleaning the rubber o-ring .