Carlos Eduardo 
Hey guys, i'm a mini2440/embedded newbie i recently got a Mini2440 (T35) arm board and want to know how can i set the LCD backlight brightness... I've tried two ways, without success: Test 1: emdebian + kernel 2.6.32.2 (compiled from FriendlyARM's DVD: linux-2.6.32.2-mini2440-20100113.tgz) : Dmesg (the part that matters... the framebuffer part) s3c2410fb: devinit s3c2410fb: got and enabled clock s3c2410fb: map_video_memory(fbi=c388ea50) map_size 155648 s3c2410fb: map_video_memory: clear ffc00000:00026000 s3c2410fb: map_video_memory: dma=33900000 cpu=ffc00000 size=00026000 s3c2410fb: got video memory s3c2410fb: LPCSEL = 0x00000f82 s3c2410fb: replacing TPAL 00000000 s3c2410fb: check_var(var=c388e820, info=c388e800) s3c2410fb: pixclk 170000, divisor is 17 s3c2410fb: s3c2410fb_activate_var: var->xres = 240 s3c2410fb: s3c2410fb_activate_var: var->yres = 320 s3c2410fb: s3c2410fb_activate_var: var->bpp = 16 s3c2410fb: setting vert: up=2, low=5, sync=2 s3c2410fb: setting horz: lft=1, rt=26, sync=5 s3c2410fb: new register set: s3c2410fb: lcdcon[1] = 0x00000878 s3c2410fb: lcdcon[2] = 0x014fc101 s3c2410fb: lcdcon[3] = 0x00c8ef00 s3c2410fb: lcdcon[4] = 0x00000004 s3c2410fb: lcdcon[5] = 0x00000b09 s3c2410fb: LCDSADDR1 = 0x19c80000 s3c2410fb: LCDSADDR2 = 0x19c92c00 s3c2410fb: LCDSADDR3 = 0x000000f0 Result: If i look at the device from a 45 degree angle, i can see the Tux logo and a console prompt (proving that LCD works just fine and it's initialized properly) but back-light is too bright (maxed out) and i don't know how to set it to a reasonable (usable) level... I've got no /dev/backlight whatsoever.... maybe udev is playing tricks on me and i need to create it manually? or maybe this kernel doesn't uses this interface and there's another way to set it... i don't really know. Test 2 : Emdebian + Jay's custom 2.6.33 (vanilla--> customized) kernel I can see the logo too, no support for buzzer (/dev/pwm doesn't exists), leds work by writing /sys/class/leds.... , and i see a 'backlight' there under leds, there IS a level file inside this backlight folder but no matter what value i put in there, it's just OFF or ON maxed out (0 is off, and anything else 1--255 is ON, maxed).... found in google another jay's post in which he's using PWM (triggers and delay_on delay_off) to try to mess with the backlight in this way, but i tried a bunch of variable combinations, and when it starts to get a bit dimmer... the screen flickering starts to become apparent ;( What should i do guys? i'm missing something here.... thanks in advance! PS: My setup is U-BOOT on nand + sd card for boot , swap and root filesystems.
