(Not sure which component to report this. Please move it to the proper component if this is the wrong one.)

After running
  . /usr/share/bug/xserver-xorg-video-radeon/script
or
  . /usr/share/bug/xserver-xorg-video-radeon/script
with certain Philips monitor attachted, the following error is reported:

...
[    3.765537] [drm] Radeon Display Connectors
[    3.781257] [drm] Initialized radeon 2.43.0 20080528 for 0000:04:00.0 on minor 1
[   89.340131] [drm:drm_edid_block_valid [drm]] *ERROR* EDID checksum is invalid, remainder is 126
[   89.341604] [drm:radeon_dvi_detect [radeon]] *ERROR* DVI-I-1: probed a monitor but no|invalid EDID

The output of get-edid |parse-edid is:

This is read-edid version 3.0.2. Prepare for some fun.
Attempting to use i2c interface
No EDID on bus 0
No EDID on bus 1
No EDID on bus 2
No EDID on bus 3
No EDID on bus 5
No EDID on bus 6
No EDID on bus 7
No EDID on bus 8
No EDID on bus 9
No EDID on bus 10
No EDID on bus 11
No EDID on bus 12
No EDID on bus 13
No EDID on bus 14
No EDID on bus 15
No EDID on bus 16
1 potential busses found: 4
256-byte EDID successfully retrieved from i2c bus 4
Looks like i2c was successful. Have a good day.
Checksum Correct

Section "Monitor"
	Identifier "247ELH"
	ModelName "247ELH"
	VendorName "PHL"
	# Monitor Manufactured week 49 of 2011
	# EDID version 1.3
	# Digital Display
	DisplaySize 520 290
	Gamma 2.20
	Option "DPMS" "true"
	Horizsync 30-83
	VertRefresh 56-76
	# Maximum pixel clock is 170MHz
	#Not giving standard mode: 1920x1080, 60Hz
	#Not giving standard mode: 1280x1024, 60Hz
	#Not giving standard mode: 1440x900, 75Hz
	#Not giving standard mode: 1440x900, 60Hz
	#Not giving standard mode: 1680x1050, 60Hz

	#Extension block found. Parsing...
	Modeline 	"Mode 16" 148.50 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync 
	Modeline 	"Mode 0" 148.50 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync 
	Modeline 	"Mode 1" 25.200 640 656 752 800 480 490 492 525 -hsync -vsync
	Modeline 	"Mode 2" 27.027 720 736 798 858 480 489 495 525 -hsync -vsync
	Modeline 	"Mode 3" 27.027 720 736 798 858 480 489 495 525 -hsync -vsync
	Modeline 	"Mode 4" 74.250 1920 2008 2052 2200 1080 1082 1087 1125 +hsync +vsync interlace
	Modeline 	"Mode 5" 27.027 1440 1478 1602 1716 480 484 487 525 -hsync -vsync interlace
	Modeline 	"Mode 6" 27.027 1440 1478 1602 1716 480 484 487 525 -hsync -vsync interlace
	Modeline 	"Mode 7" 148.500 1920 2008 2052 2200 1080 1084 1089 1125 +hsync +vsync
	Modeline 	"Mode 8" 27.000 720 732 796 864 576 581 586 625 -hsync -vsync
	Modeline 	"Mode 9" 27.000 720 732 796 864 576 581 586 625 -hsync -vsync
	Modeline 	"Mode 10" 74.250 1280 1720 1760 1980 720 725 730 750 +hsync +vsync
	Modeline 	"Mode 11" 74.250 1920 2448 2492 2640 1080 1082 1089 1125 +hsync +vsync interlace
	Modeline 	"Mode 12" 27.000 1440 1464 1590 1728 576 578 581 625 -hsync -vsync interlace
	Modeline 	"Mode 13" 27.000 1440 1464 1590 1728 576 578 581 625 -hsync -vsync interlace
	Modeline 	"Mode 14" 148.500 1920 2448 2492 2640 1080 1084 1089 1125 +hsync +vsync
	Modeline 	"Mode 15" 74.250 1280 1390 1420 1650 720 725 730 750 +hsync +vsync
	Modeline 	"Mode 17" 27.00 720 736 798 858 480 489 495 525 -hsync -vsync 
	Modeline 	"Mode 18" 74.25 1280 1390 1430 1650 720 725 730 750 +hsync +vsync 
	Modeline 	"Mode 19" 27.00 720 732 796 864 576 581 586 625 -hsync -vsync 
	Option "PreferredMode" "Mode 16"
EndSection

See also http://www.philips.nl/c-p/247E3LPHSU_00/59.9-cm-23.6-inch-e-line/specificaties