Detecting LCD Monitors.

D. Hugh Redelmeier hugh-pmF8o41NoarQT0dZR+AlfA at public.gmane.org
Tue Aug 14 00:28:41 UTC 2007


Here's a rather confusing extract from my machine's Xorg.0.log:

     1	(II) NV(0): Probing for EDID on I2C bus B...
     2	(II) NV(0): I2C device "DDC:ddc2" registered at address 0xA0.
     3	(II) NV(0): I2C device "DDC:ddc2" removed.
*    4	(--) NV(0): DDC detected a DFP:
     5	(II) NV(0): Manufacturer: DEL  Model: 4016  Serial#: 1194472500
     6	(II) NV(0): Year: 2005  Week: 51
     7	(II) NV(0): EDID Version: 1.3
     8	(II) NV(0): Digital Display Input
*    9	(II) NV(0): Max H-Image Size [cm]: horiz.: 64  vert.: 40
    10	(II) NV(0): Gamma: 2.20
    11	(II) NV(0): DPMS capabilities: Off; RGB/Color Display
*   12	(II) NV(0): First detailed timing not preferred mode in violation of standard!
*   13	(II) NV(0): redX: 0.640 redY: 0.343   greenX: 0.292 greenY: 0.611
    14	(II) NV(0): blueX: 0.146 blueY: 0.074   whiteX: 0.313 whiteY: 0.331
    15	(II) NV(0): Manufacturer's mask: 0
    16	(II) NV(0): Supported additional Video Mode:
    17	(II) NV(0): clock: 71.0 MHz   Image Size:  646 x 406 mm
    18	(II) NV(0): h_active: 1280  h_sync: 1328  h_sync_end 1360 h_blank_end 1440 h_border: 0
    19	(II) NV(0): v_active: 800  v_sync: 803  v_sync_end 809 v_blanking: 823 v_border: 0
    20	(II) NV(0): Supported additional Video Mode:
    21	(II) NV(0): clock: 268.0 MHz   Image Size:  646 x 406 mm
    22	(II) NV(0): h_active: 2560  h_sync: 2608  h_sync_end 2640 h_blank_end 2720 h_border: 0
    23	(II) NV(0): v_active: 1600  v_sync: 1603  v_sync_end 1609 v_blanking: 1646 v_border: 0
    24	(II) NV(0): Monitor name: DELL 3007WFP
    25	(II) NV(0): Serial No: JG5785CFG244
    26	(II) NV(0): EDID (in hex):
    27	(II) NV(0):     00ffffffffffff0010ac164034343247
    28	(II) NV(0):     330f01038040287828fe87a3574a9c25
    29	(II) NV(0):     13505400000001010101010101010101
    30	(II) NV(0):     010101010101bc1b00a0502017303020
    31	(II) NV(0):     360086962100001ab06800a0a0402e60
    32	(II) NV(0):     3020360086962100001e000000fc0044
    33	(II) NV(0):     454c4c20333030375746500a000000ff
    34	(II) NV(0):     004a47353738354346473234340a0007
*   35	(--) NV(0): CRTC 0 is currently programmed for DFP
*   36	(II) NV(0): Using DFP on CRTC 0
    37	(--) NV(0): Panel size is 2560 x 1600
    38	(II) NV(0): Printing DDC gathered Modelines:
    39	(II) NV(0): Modeline "1280x800"   71.00  1280 1328 1360 1440  800 803 809 823 -hsync +vsync
    40	(II) NV(0): Modeline "2560x1600"  268.00  2560 2608 2640 2720  1600 1603 1609 1646 +hsync +vsync
*   41	(II) NV(0): Panel is TMDS
    42	(--) NV(0): VideoRAM: 262144 kBytes
    43	(==) NV(0): Using gamma correction (1.0, 1.0, 1.0)
    44	(II) NV(0): <default monitor>: Using hsync range of 49.31-98.71 kHz
    45	(II) NV(0): <default monitor>: Using vrefresh range of 59.86-59.97 Hz
    46	(II) NV(0): Estimated virtual size for aspect ratio 1.6000 is 2560x1600
    47	(II) NV(0): Clock range:  12.00 to 400.00 MHz
    48	(II) NV(0): Not using default mode "640x350" (hsync out of range)

Things to note:

Line 4 says that a Digital Flat Panel was detected.  Could that be
what you are looking for?  Lines 35 and 36 also mention DFP.

Line 9 tells you the size of the display.  That could be used to tell
the aspect ratio.  As well, if this were to get into the xorg.conf
Monitor section's DisplaySize declaration, I think that X will scale
fonts to make them readable for most people.

Line 41 says that the panel is TMDS.  Perhaps that strongly suggests LCD.
  http://en.wikipedia.org/wiki/Transition_Minimized_Differential_Signaling

Line 12 says that the monitor violates some standard.

Line 12 seems to suggest that the data specifies a preferred mode.
Perhaps that is what you shuld be using.

BTW, lines 12 and 13 were actually one originally: I broke them
appart.  I would guess that this is an X bug.

Context:
- Fedora 7 x86_64
- nVidia 7800GTX
- Dell 3007FPW  2560x1600 pixels
- nv (open-source, 2d-only) driver
- xorg-x11-server 1.3.0.0-9.fc7
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