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TommyPeanuts
Asked: 2017-04-27 09:50:14 +0800 CST

17.04 Display scaling reverting to 1 after resume from suspend?

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I've recently done a clean install of 17.04 on a machine with an Nvidia 750Ti card and a Dell 4K monitor. I'm using the Nvidia binary driver 381.09.

All this works great apart from the fact that the display scaling I set in the Ubuntu Screen Display settings always reverts back to 1 when the machine resumes after suspend. I need to set it at 1.5 otherwise everything goes tiny (BTW why doesn't Ubuntu scale to a sensible default with 4K monitors?)

Does anyone else get this? I can't find any mention of it elsewhere.

BTW I've tried the Nouveau driver and that doesn't wake up my screen at all after suspend. So that route's a non-starter.

Edit: Looks like it's been reported as a confirmed bug here Will monitor to see if anything happens.

nvidia

1 Answers

  1. For anyone else being frustrated by this bug, here's a quick perl script to watch for changes in the scale_factor value and reset to whatever the value is when the script was first run:

    #!/usr/bin/perl -w
use strict;

my $dconf_line = `dconf read /com/ubuntu/user-interface/scale-factor`;
my ($scale_factor) = $dconf_line =~ m/DP1\': (\d+)/;

if ($scale_factor) {
    print STDOUT "Current value of scale_factor: $scale_factor ...\n\n";
} else {
    die "Error: cannot find scale_factor value in dconf\n(value of /com/ubuntu/user-interface/scale-factor was $dconf_line\n\n";
}

open(my $fh, "-|", "dconf watch /com/ubuntu/user-interface/scale-factor");

while (<$fh>) {
    if (m/DP1\': (?!$scale_factor)/) {
        `dconf write /com/ubuntu/user-interface/scale-factor "{'DP1': $scale_factor}"`;
        my $date = `date`;
        print STDOUT "$date -- scaling factor adjusted\n\n";
    }
}

    Just leave the script running, and it'll catch and reset any attempts to change away from the value.

    Works for me on 17.04 with unity, but it's possible that with the switch to gnome in 17.10 the value is stored in a different dconf registry key -- if so, just replace all instances of the key location in the script with the appropriate one and it should work.

    Hope this helps ...

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