How do I use kscreen?

Duncan 1i5t5.duncan at
Sat Nov 8 20:50:21 GMT 2014

Nikos Chantziaras posted on Sat, 08 Nov 2014 18:37:52 +0200 as excerpted:

> On 06/11/14 10:42, Duncan wrote:
>> Normally that "something" would be the full EDID info from the monitor
>> itself.
> I disabled the EDID in my xorg.conf (Option "UseEdidFreqs" "FALSE") and
> defined my own modes because I need refresh rates for 24p, NTSC and PAL
> content, which are not provided by computer monitor EDIDs. It's usually
> only TVs that have these.
> And indeed the NVIDIA driver doesn't use the EDID:
>    NVIDIA(0): Not using HorizSync/VertRefresh ranges from the EDID for
>    NVIDIA(0):     display device Samsung SyncMaster (DFP-3) (Using EDID
>    NVIDIA(0):     frequencies has been disabled on all display devices.)
> This is needed, because otherwise it's not possible to add custom modes,
> at least with the NVIDIA driver.

Interesting.  It's certainly possible to add custom modes/modelines for 
the Radeon driver, and I think pretty much all native drivers, with EDID 
still active.  I've been doing that here for years.

Now the driver does check that they're within the EDID frequency ranges 
for the monitor and the graphics adaptor and will normally reject any 
mode outside that range, regardless of whether it's built-in or manually 
added, and at one point with a monitor some years ago I was providing my 
own slightly fudged frequency ranges in ordered to squeeze a higher 
resolution in, but it was still taking the rest of the EDID, including 
the monitor's own resolution settings.

There is a caveat, however.  If two modes are named the same, only one 
survives.  So if one is named 1920x1080, and you want another mode like 
it but say at a different frequency, the second need named differently, 
say 1920x1080 at 50 or whatever.  The xorg.conf manpage says identically 
named custom modes override builtins.

Tho I apparently have a higher tolerance for unsyncronized updates than 
many, and as long as the frequency isn't so low it's blinking (again, 
light backgrounds make that far more noticeable), I don't care about 
update frequency so much.  I'm running all three monitors here at native 
1920x1080 full-hd resolution, at standard 60 Hz refresh, and use either 
smplayer/minitube/vlc full-screen (to one monitor) mode or kwin's opengl-
accelerated zoom, for all media content.  I haven't bothered with 
alternate resolution or frequency in some time, since I upgraded to the 
triple monitor layout at least, since I've not upgraded the xrandr-based 
script I used to use with dual-monitor.

> I have lots of modelines defined, but my default mode in xorg.conf is
> set to 1920x1080:
>    SubSection "Display"
>        Depth  24 Modes  "1920x1080 at 60"
>    EndSubSection
> And this works just fine for X, since KDM is using 1920x1080 (or
> whatever I make the default in the "Display" subsection.) It's only the
> desktop that seems to ignore that setting now. In the previous version,
> it was picking that default up without problems. Fortunately, the new
> kscreen system remembers my previous choice, so once I had set 1920x1080
> in the NVidia tool, the desktop remembered that for all future logins.
> Previously, all these settings were temporary and were lost after
> logging out.

Since kscreen runs at user login, that kdm uses the standard xorg 
defaults while kscreen was screwing them up at login isn't surprising.  I 
wouldn't have thought of that either, since I use a CLI login (on the 
1920x1080 KMS-based framebuffer) and (effectively, I've customized a 
bit...) run startx with kde as the session, from there.

But kscreen evidently ignores your xorg EDID settings and still tries to 
use them, thus originally screwing things up by trying to restore the bad 
"preferred" resolution when it didn't have a matching stored profile.

But the big point of kscreen as opposed to the older krandr is that while 
krandr only had one stored profile, kscreen has multiple profiles so it 
can track and restore to matching profile for anything you connect 
regularly, and it's good to see that once you did fix the profile, kscreen 
remembered it as it's supposed to do, and restored it on login. =:^)

Tho I suspect if you connect a second monitor, you /may/ have trouble 
with kscreen going back to the bad "preferred" setting for the first one, 
until you properly setup the new profile as well.

But it sounds like you don't mess with multi-monitor at all, so you 
shouldn't have to worry about that.  And with kscreen properly 
remembering the good settings now, looks like you're good to go. =:^)

Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman

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