How can I get my monitor's maximum resolution without the proprietary AMD graphic driver installed?
I didn't see any errors in the Xorg.0.log
file the radeon driver seems to work well so try to create a Modeline for the unsupported resolution. Open a terminal with Ctrl+Alt+t and type:
cvt 1366 768
It should return:
# 1368x768 59.88 Hz (CVT) hsync: 47.79 kHz; pclk: 85.25 MHz
Modeline "1368x768_60.00" 85.25 1368 1440 1576 1784 768 771 781 798 -hsync +vsync
Now try to create a new mode for xrandr
using this Modeline:
xrandr --newmode "1368x768_60.00" 85.25 1368 1440 1576 1784 768 771 781 798 -hsync +vsync
Finally apply the new mode to your desired output:
xrandr --addmode DVI-0 1368x768_60.00
Note: Change DVI-0 by your current active output, check the result of the xrandr
command to know which one to choose.
EDIT: How to force lightdm to use this specific resolution:
Create a shell script in /usr/bin called
lightdmxrandr.sh
containing:#!/bin/sh xrandr --newmode "1368x768_60.00" 85.25 1368 1440 1576 1784 768 771 781 798 -hsync +vsync xrandr --addmode DVI-0 1368x768_60.00 xrandr --output DisplayPort-0 --off --output DVI-0 --mode 1368x768_60.00 --pos 0x0 --rotate normal --output HDMI-0 --off
Make
/usr/bin/lightdmxrandr.sh
executable:sudo chmod +x /usr/bin/lightdmxrandr.sh
Modify your lightdm settings:
sudo gedit /usr/share/lightdm/lightdm.conf.d/50-ubuntu.conf
to add the following line:
display-setup-script=/usr/bin/lightdmxrandr.sh
This will set the login screen resolution. To set the desktop resolution, do the following:-
Open Startup Applications. One can do so from the dash.
In the startup applications window select "Add". Then give a name of your choice. Then press browse and select lightdmxrandr.sh from /usr/bin. Now select "Add". Make sure there is a tick mark before the entry you just added and then close the window.
Now reboot. Both your login screen and desktop must have the 1366x768 resolution.
PS:- Credits for the last part of the answer go to this question here.