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Old 08-11-2013, 11:23 AM   #1
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Ingenic JZ4730 framebuffer problem: /dev/fb0 is not storing the actual screen.

I have a fingerprint attendance machine with this soc
/dev # cat /proc/cpuinfo
system type : JZ4730
processor : 0
cpu model : Ingenic JZRISC V4.15
BogoMIPS : 335.05
wait instruction : yes
microsecond timers : no
tlb_entries : 32
extra interrupt vector : yes
hardware watchpoint : yes
ASEs implemented :
shadow register sets : 1
VCED exceptions : not available
VCEI exceptions : not available

The actual display is 128x64 dot monochrome LCD, but fbset is reporting
/dev # fbset

mode "240x400-0"
# D: 0.000 MHz, H: 0.000 kHz, V: 0.000 Hz
geometry 240 400 240 400 16
timings 0 0 0 0 0 0 0
accel true
rgba 5/11,6/5,5/0,0/0

I tried dumping the framebuffer, /dev/fb0 to a file, and it's actually a color image that has nothing to do what is being shown on the black and white LCD.
Actual display capture
image from /dev/fb0

What am I doing wrong here? I also tried capturing /dev/fb0 when the actual display is showing different images, and compared the binary, they are identical. It seems the /dev/fb0 does not correspond at all to the actual display.

Also some info from dmesg
jzlcd use 1 framebuffer:
jzlcd fb[0] phys addr =0x010c0000
LCDC: PixClock:6577694 LcdClock:20966400
Console: switching to colour frame buffer device 30x25
fb0: jz-lcd frame buffer device, using 256K of video memory
x:ffffffff, y:ffffffff, w:ffffffff, h:ffffffff, d:ffffffff
JzSOC: char device family.

Can someone help?


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