How to change supported Refresh rate in Linux display Driver? -

in linux frame buffer driver,it supports below resolutions , refresh rate.

cat /sys/class/graphics/fb1/modes command gives below supports

d:1600x900p-59 d:720x400p-70 v:640x480p-60 v:640x480p-75 v:800x600p-60 v:800x600p-75 v:1024x768p-60 v:1024x768p-75 v:1280x1024p-75 s:1152x864p-75 s:1280x1024p-60 d:1600x900p-59 

my question is

where these values initialized , supported in driver; refresh rate (eg : 59,70,60) because want support different refresh rate d:1600x900p-60 instead of d:1600x900p-59.

can me on this?

to chose mode listed in supported resolution type following in terminal:

xrandr -s 1600x900 -r 59 

but since mode want not listed use define new mode :

xrandr --newmode $(gtf 1600 900 60 | sed -ne 's/"//g;s/ modeline //p') 

and add list ( chose custom name of mode)

xrandr --addmode custom 1600x900_60.00 

and

xrandr -s 1600x900 -r 60