Dual monitor on Nvidia with external LCD?

[timonoj]

Hi,

I have this issue when connecting my laptop to the TV screen, an LCD with the max resolution of 1366x768x60hz. The laptop screen works at 1440x900x60hz.
When I enable TwinView on nvidia-settings, it will set the LCD as the main screen with the menu bar etc (no matter whether I tick the main screen box or not, it ignores that), and the resolution is set to 1024x768, regardless of what I choose.

I just found out that if I try something with xrandr, such as

$ xrandr --output CRT-0 --mode 1280x720 --rate 60
xrandr: Failed to get size of gamma for output default
warning: output CRT-0 not found; ignoring

at least I get the menu bar with the K button etc back to my laptop. I'm not sure of the consequences of this, but it also changed the background desktop to the default one on the LCD (remaining the same on the laptop's screen).

I also think maybe that message has something helpful? On nvidia-settings the screens are named AUO for the laptop, and CRT-0 for the LCD, connected through an standard VGA cable. Also, for some reason the xorg.conf is missing, I don't know if this is the new default on 11.10 or something went very wrong (and unnoticed) some months ago during the install...

What would you recommend me to do?

Thank you very much!


[edit] Well, at least now I know what the default desktop meant. That way, the second screen is controlled by a separated X manager, apparently. I can't drag&drop a window to the second screen to see it there. It's just controlling two independent X, and the second one can't do much (if I right click-run command, the window will pop in the laptop screen). Is there a way to enable twin view while keeping the proper resolutions? Thank you!

[SecretCode]

I also use a laptop with NVIDIA and an external screen. I had problems with having a Plasma panel on both screens, but that's another story.

What I know is this: Twinview and "separate X server" are alternatives to each other - you can't have both with the same pair of displays. With Twinview you definitely can drag windows from one to the other. With a separate X server, by design you can't, but I have not tried that setup.

Twinview has that "make this the primary display for the X screen" checkbox - and it may take a couple of tries to get it to take effect, but it generally does.

The grey area for me is how Plasma identifies the physical displays (or outputs or monitors or whatever they may be called) and how it handles placement of panels and widgets when you add or remove a display. I've had so many Plasma crashes, and so many times I've had to delete the configuration and go back to the defaults, that I have for the moment given up trying to work it out.

I have a default panel, placed at the top, and when my external screen is attached it's set to be "primary", and the panel moves to the top of that display (which is physically above my laptop). I've given up on other widgets.


Now, in terms of resolutions ... as long as you select "twinview" and "above" or "right" or something, it should work - if you select "clone" both displays will be limited to whatever common resolution it can find (do you need clone)?
If you're not cloning, setting a specific resolution instead of "Auto" may help.

If it's still troublesome, delete your /etc/X11/xorg.conf and/or your ~/.nvidia-settings-rc and start again from scratch!

[timonoj]

Thank you for your help! From what I've seen in xrandr, when you choose twinview, it kind of makes a single screen to the X, with the resolution resulting of the sum of the two screens. Something like that. So I reckon plasma should be identifying any of them like the only existing screen... But that's my thought, I didn't get as far as to get trouble on there.

Regarding my case, I indeed choose "twinview" (not clone), and "right of", and it generates an extended desktop, but in the wrong resolution. I change it manually from auto, and I set it to 1366x768, but it outputs 1024x768....and a gap missing on the left. So the laptop screen is on the left and LCD on the right. When I move the mouse from the laptop panel to the right, there's a gap missing, and then after keeping moving, it shows on the LCD monitor. There's no blank on the LCD, the 1024x768 occupies all the screen size, but there's a "virtual" blank space between the notebook panel and the LCD. This area doesn't pan automatically with the movement of the mouse.

I'll try deleting xorg.conf (I believe I don't have one) and nvidia-settings-rc as soon as I get back home, to see how it goes. Is there a way to input somewhere the manual resolution of the LCD besides in nvidia-settings (which doesn't seem to get the proper resolution right)?

[timonoj]

Ok, so I followed your tip and I insisted with nvidia-settings. Actually on the third try I got my menu bar back to the laptop! Yay
Also, after checking more resolutions manually I got the following: Whenever I try 1360x768, it fallbacks to 1024x768, but saying that it got 1360x768 right. However if I set 1152x864, the monitor displays it rather properly! (actually a bit displaced to the left, but nothing I couldn't tune).
So far, I have the following options-results:
1360x768 -> 1024x768
1152x864 -> 1152x864
1024x768 -> 1024x768

Any ideas/suggestions?

PS: Definitely I don't have an xorg.conf in the etc/X11 folder, and I deleted the nvidia-settings-rc, but with no changes in behaviour so far.

[SecretCode]

Do you have a 1366x768 resolution available? 1360x768 seems like an odd resolution to me, and my instinct is good enough for a bug report. ()

[andystmartin]

For what it's worth, I personally had no end of trouble using the proprietary nvidia drivers, xrandr, plasma, and sometimes connecting an external monitor to my laptop.

Since I have no requirements for graphical eye-candy, I reverted to the nouveau drivers and have been happy ever since. xrandr is not really supported by the nvidia drivers and has limited usefulness. Once I switched to nouveau, a simple script when I log in detects the presence of monitors and runs xrandr to configure appropriately.

Parts of my script follows. It puts the makes the external monitor the "primary" (has plasma taskbar) if it is connected. The LVDS-1 display is the laptop display.

DP=$(xrandr --query | egrep '^(DP|VGA)-[123] connected' | cut -f 1 -d ' ')

case "$DP" in
DP-?|VGA-?)
xrandr --output $DP --auto --primary --output LVDS-1 --auto --below $DP
;;
*)
xrandr --output LVDS-1 --auto
;;
esac