external screen no longer support native resolution

[Frederic Muller]

Hi!

I just upgraded to F22 and my external monitor (a Koios 24" 1920x1200)
no longer works in its native resolution. I can only get 1280 x 768 to
display.

Everything was working well before. My video chip is the Intel HD
Graphics 5500 (Broadwell GT2) (the laptop is a X1 Carbon 3rd generation).

GNOME display settings does offer the native resolution but it just
doesn't work (I get an screen switched off).

How would you troubleshooting this?

Thank you.

Fred

[Suvayu Ali]

On Tue, Jul 21, 2015 at 02:32:08PM +0700, Frederic Muller wrote:
> Hi!
>
> I just upgraded to F22 and my external monitor (a Koios 24" 1920x1200)
> no longer works in its native resolution. I can only get 1280 x 768 to
> display.
>
> Everything was working well before. My video chip is the Intel HD
> Graphics 5500 (Broadwell GT2) (the laptop is a X1 Carbon 3rd generation).
>
> GNOME display settings does offer the native resolution but it just
> doesn't work (I get an screen switched off).
>
> How would you troubleshooting this?

The first step would be to see what xrandr gives you (try -q).  If that
works, try to get it working with xrandr first.

Hope this helps,

[Frederic Muller]

On 07/21/2015 06:08 PM, Suvayu Ali wrote:
> On Tue, Jul 21, 2015 at 02:32:08PM +0700, Frederic Muller wrote:
> > Hi!
> >
> > I just upgraded to F22 and my external monitor (a Koios 24" 1920x1200)
> > no longer works in its native resolution. I can only get 1280 x 768 to
> > display.
> >
> > Everything was working well before. My video chip is the Intel HD
> > Graphics 5500 (Broadwell GT2) (the laptop is a X1 Carbon 3rd generation).
> >
> > GNOME display settings does offer the native resolution but it just
> > doesn't work (I get an screen switched off).
> >
> > How would you troubleshooting this?
>
> The first step would be to see what xrandr gives you (try -q).  If that
> works, try to get it working with xrandr first.
>
> Hope this helps,

Thanks. It actually did help and I really don't know why. I did the
xrandr -q then xrandr --output DP1 -s 1920x1200 which didn't change
anything but then after going back to display in GNOME settings and
selecting 1920x1200 resolution it worked.

Go figure...

So thank you.

Fred

[Barry Scott]

On Tue 21 Jul 2015 14:32:08 Frederic Muller wrote:
> Hi!
>
> I just upgraded to F22 and my external monitor (a Koios 24" 1920x1200)
> no longer works in its native resolution. I can only get 1280 x 768 to
> display.
>
> Everything was working well before. My video chip is the Intel HD
> Graphics 5500 (Broadwell GT2) (the laptop is a X1 Carbon 3rd generation).
>
> GNOME display settings does offer the native resolution but it just
> doesn't work (I get an screen switched off).
>
> How would you troubleshooting this?

Look in dmesg for errors. If you see problems with EDID it can
be a cable fault, try another cable.

Use xrandr --verbose to see what Xorg makes of the screen.
You should have EDID and the 1920x1080 mode should be listed.

Barry