[ltp] R51 display resolution

[Bret Comstock Waldow]

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On Sat, 09 Jul 2005 16:15, Takis Diakoumis wrote:
> Hi
>
> i'm trying to configure my display resolution at something greater than
> 1024x768. i have a R51 2887 running debian. the display chip is the
> intel 855GM.

The video display chip can do it - the monitor (LCD laptop panel) can't.  A=
n=20
external monitor plugged into the VGA out connector may, if it's built to=20
handle higher resolutions.

My T42 has a key combination (Fn+ F7) to switch between internal (LCD),=20
external (whatever's plugged into the VGA out connector) or simultaneous=20
display.  If the monitor can't do it (LCD or CRT, internal or external) it=
=20
won't display it.  In rare cases, especially some older monitors, it's=20
possible to fry the monitor by overdriving it.

There are a few tricks.  The pixels on an LCD are physical circuits - their=
=20
size doesn't change.  A CRT monitor has some minimum pixel size based on th=
e=20
masking screen/rgb phosphor dot size combination it's manufactured with, bu=
t=20
it can easily fill the screen with a lesser resolution.  In most cases,=20
selecting a lesser resolution on an LCD simply lights up that many pixels=20
(say 800x600) with a big (unused) black area around the outside.

With a framebuffer display driver you may be able to map a lesser resolutio=
n=20
to a full screen on an LCD.  I run my X GUI at the native 1400x1050 pixels =
of=20
the LCD, and use the radeon frame buffer to display text consoles=20
(Ctrl-Alt-F1)  at 1024x768 (as the text at full resolution is too tiny on a=
=20
14" display) and the frame buffer does a good job of mapping the 1024x768 t=
o=20
the physical 1400x1050 so the console uses the entire 14" screen.  There's =
a=20
big of smudging of the text characters due to the imperfect mapping, but th=
e=20
driver really does a good job.

And you can run a virtual display, with say a resolution of 1600x1200, but=
=20
showing a real window onto that virtual display of 1024x768 pixels at a tim=
e,=20
scrolling to see other corners of the virtual display.  From the looks of=20
your XFree config file below, you're set to do this - press Ctrl-Alt-+ to=20
cycle through your X resolutions.  May not be what you were hoping for,=20
though.  (Ctrl-Alt-Backspace to restart X, if you get in trouble.)

And you may arrange to have two entirely different desktop/images displayed=
 on=20
the internal LCD and an external monitor simultaneously in various=20
configurations at different resolutions.  There's much discussion in this=20
list about that.  (Hint: search the archives.  I don't use two displays.)

Cheers,
Bret

>
> i have checked the ibm website and have found drivers for windows that
> supports upto 2048x1536 and same for the lcd - info is at:
> (http://www-307.ibm.com/pc/support/site.wss/document.do?sitestyle=3Dlenov=
o&ln
>docid=3DMIGR-58208&velxr-layout=3DprintLenovo)
>
> so that confirms (??) that it can be done. problem is that X only gives
> me upto 1024x768. even when i add the relevant lines to XF86Config-4 for
> 1280x1024 they seem to be ignored. indeed, using the 855resolution
> utility it reports that the chip can do upto 1920x1440. i figure i must
> have something incorrectly configured.
>
> has anyone been able to achieve a resolution greater than 1024x768 for
> an r51 (or close relative) with the intel 855 chip???
>
> relevant sections from my XF86Config-4 are below.
>
> any suggestions would be appreciated.
> thanks
>
> Takis
>
> /etc/X11/XF86Config-4
>
> Section "Device"
> 	Identifier	"i855GM"
> 	Driver		"i810"
> 	BusID		"PCI:0:2:0"
> EndSection
>
> Section "Monitor"
> 	Identifier	"Generic Monitor"
> 	HorizSync	30-60
> 	VertRefresh	50-60
> 	Option		"DPMS"
> EndSection
>
> Section "Screen"
> 	Identifier	"Default Screen"
> 	Device		"i855GM"
> 	Monitor		"Generic Monitor"
> 	DefaultDepth	24
> 	SubSection "Display"
> 		Depth		1
> 		Modes		"1280x1024" "1280x960" "1152x864" "1024x768" "800x600"
> "640x480"
> 	EndSubSection
> 	SubSection "Display"
> 		Depth		4
> 		Modes		"1280x1024" "1280x960" "1152x864" "1024x768" "800x600"
> "640x480"
> 	EndSubSection
> 	SubSection "Display"
> 		Depth		8
> 		Modes		"1280x1024" "1280x960" "1152x864" "1024x768" "800x600"
> "640x480"
> 	EndSubSection
> 	SubSection "Display"
> 		Depth		15
> 		Modes		"1280x1024" "1280x960" "1152x864" "1024x768" "800x600"
> "640x480"
> 	EndSubSection
> 	SubSection "Display"
> 		Depth		16
> 		Modes		"1280x1024" "1280x960" "1152x864" "1024x768" "800x600"
> "640x480"
> 	EndSubSection
> 	SubSection "Display"
> 		Depth		24
> 		Modes		"1280x1024" "1280x960" "1152x864" "1024x768" "800x600"
> "640x480"
> 	EndSubSection
> EndSection

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