Wide screen LCD monitors and X

I am thinking to buy a wide screen LCD monitor, but I seem to
recall having heard rumors about difficulties configuring X to support
the resolutions (such as 1680x1050) that such monitors offer. Is there
any truth in this? If anybody has experience with this type of monitors
your feedback would be much appreciated.

On Mon, 04 Jun 2007 04:08:34 +0000, Harold Weissman wrote:

> I am thinking to buy a wide screen LCD monitor, but I seem to recall
> having heard rumors about difficulties configuring X to support the
> resolutions (such as 1680x1050) that such monitors offer. Is there any
> truth in this? If anybody has experience with this type of monitors your
> feedback would be much appreciated.

As long as your graphics card supports that resolution you won't have any
trouble. I have the Dell 24", 1920x1200, and a Compaq laptop, 1650x1080,
and both work fine. Prior to FC4 I had to configure the xorg.conf on my
laptop by hand but it's been automatic since FC4 came out (which was two
years ago). BTW I highly recommend the Dell, it's sharp, clear, and
vibrant. It's the best looking monitor I've ever had.

General Schvantzkoph writes:

> On Mon, 04 Jun 2007 04:08:34 +0000, Harold Weissman wrote:
>
>> I am thinking to buy a wide screen LCD monitor, but I seem to recall
>> having heard rumors about difficulties configuring X to support the
>> resolutions (such as 1680x1050) that such monitors offer. Is there any
>> truth in this? If anybody has experience with this type of monitors your
>> feedback would be much appreciated.
>
> As long as your graphics card supports that resolution you won't have any
> trouble. I have the Dell 24", 1920x1200, and a Compaq laptop, 1650x1080,
> and both work fine. Prior to FC4 I had to configure the xorg.conf on my
> laptop by hand but it's been automatic since FC4 came out (which was two
> years ago). BTW I highly recommend the Dell, it's sharp, clear, and
> vibrant. It's the best looking monitor I've ever had.

I had problems that I wasn't able to work out.
This was with a TV that could double as a monitor.
The native resolution was some odd number like 1368x????.
Under Linux the monitor would complain that it didn't support the
mode. This was with an Intel graphics adapter. I posted here
for help but got no response.
It does work in a slightly less than optimal resolution.

From Google,
I got the feeling I might get a solution on the Xorg forums but since
it wasn't my system I didn't go any farther.

Harold Weissman wrote:
> I am thinking to buy a wide screen LCD monitor, but I seem to
> recall having heard rumors about difficulties configuring X to support
> the resolutions (such as 1680x1050) that such monitors offer. Is there
> any truth in this? If anybody has experience with this type of monitors
> your feedback would be much appreciated.

I bought a ViewSonic VX2245 last Friday at Costco. It hooked up to
Mandriva 2007.0 with an nVidia FX6600 card without any problems at all.
I'm runnng it at 1680x1050. I like it a lot.

Good luck....

--
PLEASE post a SUMMARY of the answer(s) to your question(s)!
Show Windows & Gates to the exit door.
Unless otherwise noted, the statements herein reflect my personal
opinions and not those of any organization with which I may be affiliated.

Dan Espen wrote:

>
> I had problems that I wasn't able to work out.
> This was with a TV that could double as a monitor.
> The native resolution was some odd number like 1368x????.
> Under Linux the monitor would complain that it didn't support the
> mode. This was with an Intel graphics adapter. I posted here
> for help but got no response.
> It does work in a slightly less than optimal resolution.

For some bizarre reason, TV panels use 1368 x 762 or something like
that. You need to use a slightly different resolution; you also need to
twiddle your modeline to get rid of horrible overscan.

Visit the Mythtv.org wiki if you need to know more. Getting LCD TVs to
work with computers is pretty much a dark science, and the a**hole
manufacturers aren't any help at all.

--Yan

On Mon, 04 Jun 2007 14:55:39 +0000, Kevin the Drummer wrote:

> Harold Weissman wrote:
>> I am thinking to buy a wide screen LCD monitor, but I seem to
>> recall having heard rumors about difficulties configuring X to support
>> the resolutions (such as 1680x1050) that such monitors offer. Is there
>> any truth in this? If anybody has experience with this type of monitors
>> your feedback would be much appreciated.
>
> I bought a ViewSonic VX2245 last Friday at Costco. It hooked up to
> Mandriva 2007.0 with an nVidia FX6600 card without any problems at all.
> I'm runnng it at 1680x1050. I like it a lot.

Thanks for your reply, which I find encouraging, taking into
account that I have an nVidia card - a 7100GS, I believe. Now does your
setup work with both the X.Org driver nv and the nVidia driver nvidia?
Also did you have to tinker with your xorg.conf file, or it did just work?

Harold Weissman wrote:
>On Mon, 04 Jun 2007 14:55:39 +0000, Kevin the Drummer wrote:
>
>> Harold Weissman wrote:
>>> I am thinking to buy a wide screen LCD monitor, but I seem to
>>> recall having heard rumors about difficulties configuring X to support
>>> the resolutions (such as 1680x1050) that such monitors offer. Is there
>>> any truth in this? If anybody has experience with this type of monitors
>>> your feedback would be much appreciated.
>>
>> I bought a ViewSonic VX2245 last Friday at Costco. It hooked up to
>> Mandriva 2007.0 with an nVidia FX6600 card without any problems at all.
>> I'm runnng it at 1680x1050. I like it a lot.
>
> Thanks for your reply, which I find encouraging, taking into
>account that I have an nVidia card - a 7100GS, I believe. Now does your
>setup work with both the X.Org driver nv and the nVidia driver nvidia?
>Also did you have to tinker with your xorg.conf file, or it did just work?

With "odd" configurations you'll likely need to tinker
with xorg.conf, but it need not be difficult *if* you have
an LCD with a digital interface. (An analog interface is
only slightly more critical. A CRT is much more complex.)

First, for any given driver, there is a maximum
resolution that it will handle. Equally, for any given
video card there is a maximum resolution too. The
lesser of those is the best you can do. But today most
drivers and cards will handle higher resolution than you
are likely to encounter. (A quick google search didn't
tell me much about either your card or the nvidia and nv
drivers, but I'd be extremely surprised if 1680x1050
isn't well below the upper limit.)

The trick is, if there is no "VESA standard" mode that
you want, you have to define a mode which the monitor
can handle.

You've seen "ModeLine" entries for Xorg.conf files...
here's what you need to do to define one for an LCD with a
digital interface. This is a modeline, which I'll use
as an example:

ModeLine "1680x1050" 100.00 \
1680 1696 1612 1628 \
1050 1055 1060 1070

The identifier by which this mode will be known is "1680x1060".
You can use any name you want. It could be "1024x768" too, or
"HiResolution". But if it has the same name as a built in mode,
the built in mode will not be available.

The 100.00 is a value in MHz for the dot clock
frequency. With an LCD the only restriction is that it
fall within the range that the LCD can use, which will
probably be something like 0 to 300 MHz. Sticking to
some value between say, 20 MHz and 160 MHz is just about
guaranteed to work with any LCD.

The next four entries define the horizontal timing.
They are, in order, known as "hdisp", "hsyncstart",
"hsyncend", and "htotal". They are "timing" values,
measure in pixels.

With an LCD, only the first and the last are actually
important. The first, "hdisp" is the horizontal
resolution, so for a 1680x1050 mode, it is 1680. The
hsyncstart, hsyncend, htotal values must each be larger
than the previous, and must be divisible by 8. They
make no difference to an LCD monitor, but X calculates
what they would do to a CRT, and will refuse to accept
them unless it adds up right. If they don't... the
horizontal sync rate will be out of range, and the
solution is to provide xorg.conf with an acceptable
range. See below on setting the HorizSync range.

The next for entries define the vertical timing. The
values are in horizontal lines (rather than the pixels
used for horizontal timing). Same as above, except
there the values must be divisible by 1 rather than 8,
and the xorg.conf range of interest is VertRefresh.

So, for a 1680x1050 mode, the first value for horizontal
and vertical is known. The next two don't make any
difference. The other two? This is what they do:

htotal * vtotal * Vertical_Refresh_Rate = Dot_Clock_Rate

The Dot Clock Rate, as mentioned above has to be within
the whatever range the monitor can handle. The Vertical
Refresh Rate is ignored by an LCD monitor (but X
compares it to either a default range or to one set in
Xorg.conf with VertRefresh, and won't run if it is not
"valid"). Nice numbers are refresh rates are 20 to 80
Hz.

So lets try an odd set of values, and see what ball park
we land in. (I arrived at these simply by adding 16 to
each horizontal timing value, and 5 to each vertical
timing value.)

ModeLine "1680x1050" ??? 1680 1696 1612 1628 1050 1055 1060 1065

1628 * 1065 * 60 gives a dot clock rate of 104.03 Mhz.

Not bad! Here is a probaby useful mode definition for you:

ModeLine "1680x1050" 104.0 1680 1696 1612 1628 1050 1055 1060 1070

If you want to experiment, you can change values and
move the refresh rate around or move the dot_clock rate
up or down.

There are two values you might need to set in xorg.conf
in order to allow X to use any given mode. A monitor
section might look like this,

Section "Monitor"
Identifier "Monitor0"
VendorName "BrandX_Monitor"
ModelName "LCD-TV"
HorizSync 0-120
VertRefresh 0-90
Gamma 0.9
Option "DPMS"
EndSection

The Identifier tag is required, and the name can be
anything you choose. Other sections will refer to this
section by that name. The VendorName and ModelName are
optional; X ignores them and they are for your
information. I've included the "Gamma" and the "Option"
tags just for information, to show what can be done.

The two important tags, when defining a mode, are the
HorizSync and the VertRefresh values.

HorizSync is a value or a range of values in MHz. It is
entirely possible that a given valid modeline will
result in calculation of a horizontal sync rate that is
higher than the default, and X will refuse to accept the
mode! With an LCD, if X complains that the horizontal
sync is out of range, set it to something as above. The
same applies to the "refresh" rate, and if that is the
complaint, set it to a range such as above. (Both of
those ranges would be dangerous with a CRT! They simply
have no meaning with an LCD.)

I don't even remember how to calculate the horizontal
sync rate from the modeline values. It is no important
to know. But I did do one modeline for my laptop that
was rejected by X for being out of range, and had to
set the range as described above.

--
Floyd L. Davidson
Ukpeagvik (Barrow, Alaska) floyd-at-apaflo.com

At work I'm running dual 24" flat screens at 1680x1050 each. Lots of
desktop space. This is using an nvidia video card (forget which model)
under Ubuntu. At home I have dual 22" flat screens but haven't
configured for dual screen model. I have an ATI card at home, which
seems to be a little trickier when it comes to dual screen
configuration. Since I'm planning to get an Nvidia card very soon, I
decided to not bother with fighting with the ATI configuration.


Harold Weissman wrote:
> I am thinking to buy a wide screen LCD monitor, but I seem to
> recall having heard rumors about difficulties configuring X to support
> the resolutions (such as 1680x1050) that such monitors offer. Is there
> any truth in this? If anybody has experience with this type of monitors
> your feedback would be much appreciated.

> As long as your graphics card supports that resolution you won't have
> any trouble.

Your card has to support it, and the driver for the card has to support
it. Although you can generally setup a lower resolution if it doesn't.
Your aspect ratio may get a little odd.

I have a compaq with a 1280x800 screen. The framebuffer console looks
odd at 1024x768 resolution. And mplayer stretches things under xv. The
workarounds are to use -vo x11, or -monitoraspect 1.6 to get a more
normal picture. They say TV adds ten pounds, widescreen monitors add one
hundred and ten.

I demand that Ogre may or may not have written...

> At work I'm running dual 24" flat screens at 1680x1050 each. Lots of
> desktop space. This is using an nvidia video card (forget which model)
> under Ubuntu. At home I have dual 22" flat screens but haven't configured
> for dual screen model. I have an ATI card at home, which seems to be a
> little trickier when it comes to dual screen configuration. Since I'm
> planning to get an Nvidia card very soon, I decided to not bother with
> fighting with the ATI configuration.
[snip]

Something like this, using the X.org ATI driver. (I have no idea whether
it'll work with the taintware.) "Left monitor" is connected to the VGA
("CRT2") output, and "Right monitor" is connected to the DVI output.

You may need to disable EXA with some versions of the driver. Also, while
OpenGL should work, it will definitely not work (given the configuration
below) on the rightmost 40% of the right-hand monitor with R200-based
hardware, e.g. Radeon 9200 or 9250. (You can work around this by arranging
the monitors vertically and using Above or Below in place of LeftOf.)

MergedNonRectangular is best left enabled. It's needed if you have, for
example, a 1024x768 monitor and a 1280x1024 monitor and you intend to use
both at their native resolutions.

[...]
Section "Device"
Identifier "Radeon 9200"
Driver "radeon"
Option "AGPMode" "8"
Option "AGPFastWrite" "On"
Option "AGPSize" "128"
Option "DynamicClocks" "on"
Option "RenderAccel" "On"
Option "AccelMethod" "EXA"
Option "AccelDFS" "on"
Option "EnablePageFlip" "On"
Option "SubPixelOrder" "NONE"
Option "MergedFB" "On"
Option "MergedNonRectangular" "On"
# Option "MergedXineramaCRT2IsScreen0" "1"
Option "CRT2Position" "LeftOf"
Option "MetaModes" "1280x1024-1280x1024 1024x768-1024x768 800x600-800x600 640x480-640x480 1280x1024 1024x768 800x600 640x480"
EndSection

Section "Monitor"
Identifier "Left monitor"
Option "DPMS"
EndSection

Section "Monitor"
Identifier "Right monitor"
Option "DPMS"
EndSection

Section "Screen"
Identifier "Left monitor"
Device "Radeon 9200"
Monitor "Left monitor"
DefaultDepth 24
SubSection "Display"
Virtual 2560 1024
Depth 24
Modes "1280x1024" "1024x768" "800x600" "640x480" "640x400" "400x300" "320x240"
EndSubSection
EndSection

Section "Screen"
Identifier "Right monitor"
Device "Radeon 9200"
Monitor "Right monitor"
DefaultDepth 24
SubSection "Display"
Virtual 2560 1024
Depth 24
Modes "1280x1024" "1024x768" "800x600" "640x480" "640x400" "400x300" "320x240"
EndSubSection
EndSection

Section "ServerLayout"
Identifier "Default Layout"
Screen 0 "Right monitor"
Screen 1 "Left monitor" LeftOf "Right monitor"
InputDevice "Generic Keyboard"
InputDevice "USB Mouse" "CorePointer"
EndSection
[...]

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