[EdLUG] Graphics issues

[Edinburgh Linux Users Group]

On 2016.11.12 00:45, Edinburgh Linux Users Group wrote:
> Hi all,

> 
> So, additional info:
> 
> The desktop environment is Cinnamon
> There is indeed a display settings dialog box which does change the
> settings (but sometimes causes a freeze) but the settings are not
> preserved, which is the only reason I looked into xrandr in the first
> place.
> The screen resolutions I am trying to hit are either 1280x720 or
> 1360x768,
[snip]

> On line 181 it says "....switch to mode 1920x1080 at 60.0..." still as
> part of
> boot (I presume) but I don't know why it picks that.
> Other than that, I'm not sure what I'm looking for.

That's Xorg starting up and using the automatically detected  
1920x1080 at 60.0 native resolution of the display.
We probably have different views if its a part of the boot process
or not.  I use a console logon and start the desktop myself,
so I don't view Xorg startup as part of boot.  Users with a
graphical log in probably do, since Xorg is required to display the
login screen.

Reading man intel, the man page for the Intel video driver, makes
it look like the driver doesn't need anything special to make it provide
other resolutions, as long as they are advertised in the EDID data
read from the display. Some drivers list them in the log, some don't

Lets try the easy bit first.  On its own, it may not be sufficient.
Make a file /etc/X11/xorg.conf with the following content.


Section "Screen"
    Identifier  "Screen 1"
    DefaultDepth 24

    Subsection "Display"
        Depth       24
        Modes        "1280x720" "1360x768" "800x600"                  
        ViewPort    0 0
    EndSubsection
EndSection

The file needs to be  -rw-r--r-- 1 root root

man xorg.conf will make your eyes glaze over but it will explain
what all those lines do.

This should cause xorg to start in  "1280x720" mode
providing that mode is defined elsewhere.  If not, you can read 
all about it in /var/log/Xorg.0.log
It will try all three modes before it gives up and uses the default
1920x1080.
Pastebin the log again so we can see what actually happened. 

If it fails because the modes are not defined, the next step 
is to define them. 

Don't be too surprised if you get 800x600. Everything working
in a non default mode is a big step in the right direction.
Making it the right mode is just fine tuning.

Oh, one odd thing that might happen is that you get a virtual 
screen size of 1920x1080 and a viewport within it of one of the
Modes.  The viewport follows the mouse as you approach the
edges of the displayed area. Think of it as looking at a big 
scene (the virtual desktop) through a smaller aperture, 
(the viewport) which you can slide around.  I've not used
this feature for a long time. 

The 
ViewPort    0 0  
says to start with the viewport in the top
left of the virtual desktop.

[snip original material]

Regards,

Roy Bamford