howto use kdrive/fbdev with monochrome displays?

[Dushara Jayasinghe]

Hi all,

This is essentially a repost of 
(http://lists.x.org/archives/xorg-devel/2011-April/021370.html) with the 
problem (hopefully) more clearly explained.

I need to use Xfbdev in xorg server 1.7.5 for an embedded device with a 
240x128 monochrome display. I have tweaked an existing kernel FB driver.

The FB config is:

# fbset -i

mode "240x128-158"
     # D: 5.000 MHz, H: 20.325 kHz, V: 157.560 Hz
     geometry 240 128 240 128 1
     timings 200000 3 1 0 0 2 1
     rgba 0/0,0/0,0/0,0/0
endmode

Frame buffer device information:
     Name        : DISP0 BG
     Address     : 0x908e8000
     Size        : 4096
     Type        : PACKED PIXELS
     Visual      : MONO01
     XPanStep    : 1
     YPanStep    : 1
     YWrapStep   : 0
     LineLength  : 32
     Accelerator : No

The Visual setting is one of the changes I have made.

The FB driver itself works as expected when I run:

# cat 4k_image_file > /dev/fb0

Initially I couldn't even start Xfbdev until I applied this 
(http://lists.x.org/archives/xorg-devel/attachments/20110414/c15d2fb7/attachment.asc) 
patch.

Now Xfbdev starts without a problem (it spits out the following few 
lines to the console):

# Xfbdev
294:depth=1, bpp=1
KdSetPixmapFormats:1166 bpp[0] = 1
KdSetPixmapFormats:1172: Got here
[dix] Could not init font path element /usr/share/fonts/X11//TTF/, 
removing from list!
[dix] Could not init font path element /usr/share/fonts/X11//OTF, 
removing from list!
[dix] Could not init font path element /usr/share/fonts/X11//Type1/, 
removing from list!

The issue is, when I run a test app (xlogo in this case), nothing is 
displayed on the screen.

I also ran the following test (while Xfbdev is running):

# cat image_with_all_pixes_set >/dev/fb0
# xlogo

When I ran xlogo, the pixels in one rectangular section of the display 
were turned off. So it looks like X is accessing the display buffer 
correctly, but somehow looses the pixel depth info.

Can anyone give any hints on getting it to work properly?

Thank you

Dushara