xorg.conf PreferredMode resolution ignored in ATI video driver

Don Waugaman dpw at cs.arizona.edu
Mon Jun 23 08:14:22 PDT 2008


I have an asymmetric dualhead setup - 1920x1200 LCD on the left,
1600x1200 CRT on the right - and I'm trying to get a static xorg.conf
setup working without resorting to xrandr every time I log in.  (Getting
the screen resolution to native on the LCD monitor under GDM would be a

I'm using Fedora 9 with xorg-x11-drv-ati-6.8.0-14 on an ATI 9550-based
card, by the way.

Upon X startup, the LCD sets itself to 1600x1200:

Screen 0: minimum 320 x 200, current 3520 x 1200, maximum 3520 x 1200
VGA-0 connected 1600x1200+1600+0 (normal left inverted right x axis y
axis) 0mm x 0mm
   1600x1200 at 75Hz   75.0*+
   1360x768       59.8  
   1152x864       60.0  
   1024x768       60.0  
   800x600        60.3  
   640x480        59.9  
DVI-0 connected 1600x1200+0+0 (normal left inverted right x axis y axis)
518mm x 324mm
   1920x1200      60.0 +   60.0  
   1600x1200      60.0*    60.0  
   1680x1050      60.0  
   1600x1024      60.2  
   1400x1050      74.8     70.0     60.0  
   1280x1024      75.0     60.0     60.0  
   1440x900       59.9  
   1280x960       60.0     60.0  
   1360x768       59.8  
   1152x864       75.0     75.0     75.0     70.0     60.0  
   1024x768       75.1     75.0     70.1     60.0  
   832x624        74.6  
   800x600        72.2     75.0     60.3     56.2  
   640x480        75.0     72.8     72.8     75.0     66.7     60.0
   720x400        70.1  
S-video disconnected (normal left inverted right x axis y axis)

I can change it to use 1920x1200, and also rebase the VGA to the
screen's right to eliminate the overlap, but I'd prefer to not have to
do this every time I log in.

I noticed the following lines in my Xorg.0.log:

(II) RADEON(0): Using user preference for initial modes
(II) RADEON(0): Output VGA-0 using initial mode 1600x1200 at 75Hz
(II) RADEON(0): Output DVI-0 using initial mode 1600x1200

which seems odd since my preference in the file is for the 1920x1200
mode.  Is there a bug in the X server preventing this from being
selected somehow?  Is it selecting a mode to match the CRT head?

Also, periodically the X server's CPU utilization goes through the roof,
and interactivity pauses briefly.  After about 3-5 seconds, it picks
back up again.  These pauses are annoying, and they really interfere
with the work cycle - is there a way to figure out why this is happening
and what can be done about it?

If there is a better forum for asking these kinds of questions, feel
free to direct me to it.

I'm attaching my current xorg.conf, I can send the server log as well if
it would help, but it's rather larger and I'd hate to take up so much

Thanks for your attention and any help you can provide.

- Don Waugaman

-------------- next part --------------
# Xorg configuration created by system-config-display

Section "ServerLayout"
	Identifier	"MergeFB Layout"
	Screen		"Screen0"	0 0
	InputDevice	"Keyboard0"	"CoreKeyboard"
	InputDevice	"Mouse0"	"CorePointer"

Section "Files"

# Multiple FontPath entries are allowed (they are concatenated together)
# By default, Red Hat 6.0 and later now use a font server independent of
# the X server to render fonts.

	FontPath	"unix/:7100"


Section "ServerFlags"
	Option		"AIGLX" "on"

Section "InputDevice"

# Specify which keyboard LEDs can be user-controlled (eg, with xset(1))
#	Option	"Xleds"		"1 2 3"
# To disable the XKEYBOARD extension, uncomment XkbDisable.
#	Option	"XkbDisable"
# To customise the XKB settings to suit your keyboard, modify the
# lines below (which are the defaults).  For example, for a non-U.S.
# keyboard, you will probably want to use:
#	Option	"XkbModel"	"pc102"
# If you have a US Microsoft Natural keyboard, you can use:
#	Option	"XkbModel"	"microsoft"
# Then to change the language, change the Layout setting.
# For example, a german layout can be obtained with:
#	Option	"XkbLayout"	"de"
# or:
#	Option	"XkbLayout"	"de"
#	Option	"XkbVariant"	"nodeadkeys"
# If you'd like to switch the positions of your capslock and
# control keys, use:
#	Option	"XkbOptions"	"ctrl:swapcaps"
# Or if you just want both to be control, use:
#	Option	"XkbOptions"	"ctrl:nocaps"
	Identifier  "Keyboard0"
	Driver		"kbd"
	Option		"XkbModel"	"pc105"
	Option		"XkbLayout"	"us"

Section "InputDevice"
	Identifier	"Mouse0"
	Driver		"mouse"
	Option		"Protocol"	"IMPS/2"
	Option		"Device"	"/dev/input/mice"
	Option		"ZAxisMapping"	"4 5"
	Option		"Emulate3Buttons"	"no"

Section "Monitor"
	Identifier	"DVI-0"
	VendorName	"Samsung"
	ModelName	"BW245"
	DisplaySize	518	324
	Option		"dpms"	"on"
	HorizSync	30.0 - 81.0
	VertRefresh	56.0 - 75.0
	Modeline	"1920x1200" 154.0 1920 1968 2000 2080 1200 1203 1209 1235 -hsync +vsync
	Option		"PreferredMode"	"1920x1200"

Section "Monitor"
	Identifier	"VGA-0"
	VendorName	"Hitachi (Sun OEM)"
	ModelName	"CM751-a-like"
	DisplaySize	360	270
	Option		"dpms" "on"
	Modeline	"1600x1200 at 75Hz" 202.5  1600 1664 1856 2160  1200 1201 1204 1250  +HSync +Vsync
	Option		"PreferredMode"	"1600x1200 at 75Hz"
	Option		"RightOf"	"DVI-0"

Section "Device"
	Identifier	"Videocard0"
	Driver		"radeon"
	VendorName	"ASUS"
	BoardName	"A9950 (ATI Radeon 9550)"
	Option		"GARTSize" "256"
	BusID		"PCI:2:0:0"
	Option		"AccelMethod"	"EXA"
	Option		"Monitor-DVI-0"	"DVI-0"
	Option		"Monitor-VGA-0"	"VGA-0"

Section "Screen"
	Identifier	"Screen0"
	Device		"Videocard0"
#	Monitor		"DVI Monitor" #  Added this here - does it work?  No
#	Monitor		"VGA Monitor" #  Added this as well
	DefaultDepth	24
	SubSection "Display"
		Virtual	3520 1200
		Depth	24

Section	"Extensions"
	Option	"Composite"	"Enable"

Section "DRI"
	Group		0
	Mode		0666

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