Detecting LCD Monitors.

[Lennart Sorensen]

On Mon, Aug 13, 2007 at 04:49:31PM -0400, Colin McGregor wrote:
> I tried posting a response earlier, and possibly due
> to size (the xorg.0.log file is LONG) it hasn't gone
> through. Regardless I suspect the log file will not be
> of much use as the LCD screen I am using on my test
> box has a max. resolution of 1024 x 768. So, not the
> ideal source of help in this situation. I will plan to
> pick-up some sort of wide screen LCD later this week
> to get to the bottom of all this...
>
> Yes, only there is no way that I can see to tell if I
> am dealing with an LCD. I do know that there have been
> a SMALL number of CRT based non-4:3 aspect ratio
> monitors, those have been MOST unusual (a quick search
> only turned up the Sony GDM-FW900, but no doubt there
> have been a few others). Regardless, if I see a
> non-4:3 aspect ratio screen I can be FAIRLY sure I am
> dealing with a LCD screen.
> 
> Bottom line in all this is to make sure that what ever
> hardware this live CD is thrown at, the screen will
> look GOOD, and show at least a 1024 x 768 screen.
> PERIOD!! My "main" home machine has a big bad 21" CRT
> screen, which I am happy to run at 1600x1200, numbers
> that some visitors to my place (like say my mother)
> find too small to be readable... Okay, so if I take
> that machine and go to say 1024 x 768 I know everyone
> (who doesn't have serious vision problems) will find
> readable. Problem with LCD screens is I don't know if
> 1024x768 will look good (on my test box the LCD at
> 1024x768 is great, but then that is what that LCD
> screen was made to do...).

There is also the annoying issue that 1280x1024 CRTs are 4:3 while a
1280x1024 LCD is 5:4 (as far as I can tell).  Not that you need a
different X config, and hopefully X would read the screen dimensions by
edid and get the aspect right.  Well the 1280x1024 CRTs were always
scewed it seemed.

We have some 19" LCDs here at work which are 1280x1024 5:4 and the edid
data if I run 'get-edid|parse-edid' only returns 1280x1024 as a defined
mode.  I think a CRT usually returns more (can't really check since my
nvidia doesn't seem to like get-edid).

My home machine with a 21" CRT shows this in the X log:

(II) NV(0): Manufacturer's mask: 0
(II) NV(0): Supported Future Video Modes:
(II) NV(0): #0: hsize: 1600  vsize 1200  refresh: 85  vid: 22953
(II) NV(0): #1: hsize: 1600  vsize 1200  refresh: 75  vid: 20393
(II) NV(0): #2: hsize: 1024  vsize 768  refresh: 85  vid: 22881
(II) NV(0): #3: hsize: 1152  vsize 864  refresh: 85  vid: 22897
(II) NV(0): #4: hsize: 800  vsize 600  refresh: 85  vid: 22853
(II) NV(0): #5: hsize: 1800  vsize 1440  refresh: 75  vid: 36802
(II) NV(0): #6: hsize: 640  vsize 480  refresh: 85  vid: 22833
(II) NV(0): Supported additional Video Mode:
(II) NV(0): clock: 157.5 MHz   Image Size:  364 x 291 mm
(II) NV(0): h_active: 1280  h_sync: 1344  h_sync_end 1504 h_blank_end 1728 h_border: 0
(II) NV(0): v_active: 1024  v_sync: 1025  v_sync_end 1028 v_blanking: 1072 v_border: 0
(II) NV(0): Ranges: V min: 48  V max: 170 Hz, H min: 30  H max: 130 kHz, PixClock max 290 MHz
(II) NV(0): Monitor name: DELL P1130
(II) NV(0): Serial No: 6D25124B60FL

So in this case, 1600x1200 is a good choice (mode #0), while 1800x1440
works, it isn't as clear or recommended.

--
Len Sorensen
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