[Bug 1669] New: default mode order prevails over the recommended mode on LCD

bugzilla-daemon at freedesktop.org bugzilla-daemon at freedesktop.org
Mon Oct 18 21:50:38 PDT 2004

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           Summary: default mode order prevails over the recommended mode on
           Product: xorg
           Version: 6.7.0
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: Server/general
        AssignedTo: xorg-bugzilla-noise at freedesktop.org
        ReportedBy: apodtele at ucsd.edu

Xorg probes and assigns display modes from the highest refresh rate to the 
lowest for a given resolution. Hence, the highest allowed refresh rate is 
chosen as the default. This was historically right and sound for CRT monitors. 
This is a wrong assumption for LCDs. My display, Dell 1703FP, actually prefers 
a lower 1280x1024 at 60Hz mode instead of the allowed 1280x1026 at 75Hz. The bug is 
that my display actually _REPORTS_ the preferable rate, while Xorg ignores it. 
Here is the relevant parts of the log file: 
(II) R128(0): VESA VBE DDC supported 
(II) R128(0): VESA VBE DDC Level 2 
(II) R128(0): VESA VBE DDC transfer in appr. 2 sec. 
(II) R128(0): VESA VBE DDC read successfully 
(II) R128(0): Manufacturer: DEL  Model: 3010  Serial#: 1095191382 
(II) R128(0): Year: 2004  Week: 35 
(II) R128(0): EDID Version: 1.3 
(II) R128(0): Analog Display Input,  Input Voltage Level: 0.700/0.300 V 
(II) R128(0): Sync:  Separate  Composite  SyncOnGreen 
(II) R128(0): Max H-Image Size [cm]: horiz.: 34  vert.: 27 
(II) R128(0): Gamma: 2.20 
(II) R128(0): DPMS capabilities: StandBy Suspend Off; RGB/Color Display 
(II) R128(0): Default color space is primary color space 
(II) R128(0): First detailed timing is preferred mode 
(II) R128(0): Supported additional Video Mode: 
(II) R128(0): clock: 108.0 MHz   Image Size:  338 x 270 mm 
(II) R128(0): h_active: 1280  h_sync: 1328  h_sync_end 1440 h_blank_end 1688 
h_border: 0 
(II) R128(0): v_active: 1024  v_sync: 1025  v_sync_end 1028 v_blanking: 1066 
v_border: 0 
(--) R128(0): Virtual size is 1280x1024 (pitch 1280) 
(**) R128(0): *Default mode "1280x1024": 135.0 MHz, 80.0 kHz, 75.0 Hz 
(II) R128(0): Modeline "1280x1024"  135.00  1280 1296 1440 1688  1024 1025 
10281066 +hsync +vsync 
(**) R128(0):  Default mode "1280x1024": 108.0 MHz, 64.0 kHz, 60.0 Hz 
(II) R128(0): Modeline "1280x1024"  108.00  1280 1328 1440 1688  1024 1025 
10281066 +hsync +vsync 
I was able to override the default mode order by custom ModeLine. I wish X.org 
respected the prefered mode in the firstplace when the monitor is plugedin. For 
example, read-edid-1.4.1 gets it right.        
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