The function

static void gumstix_lcd_backlight(int on_or_off) 

is what you probably want to call from kernel space -- you'd probably need to export it, though you might be able to drill down from the machine object somehow -- I'd check how the fbcon driver ends up calling it.  Actually, you probably want to call something upstream of that to tell the fbcon driver to put itself in low power/blank mode, and that'll call the gumstix_lcd_backlight function.

C

On Sep 29, 2007, at 5:34 AM, Heilpern, Mark wrote:

I think that using the file system isn't an option since I need access from a driver. I could write a helper app that interacts with my driver, but if there's a more clean way to do this from kernel space directly, I'd prefer that.
 
Thanks,
Mark
 


From: gumstix-users-bounces@lists.sourceforge.net on behalf of Craig Hughes
Sent: Fri 9/28/2007 4:28 PM
To: General mailing list for gumstix users.
Subject: Re: [Gumstix-users] How to output text to the framebufferconsoledurring boot, and disable the blinking cursor?

On Sep 28, 2007, at 11:05 AM, Heilpern, Mark wrote:

> I would like to be able to enable / disable the LCD from a driver
> module. I see that I can dim the backlighting by controlling 
> GPIO17. Is
> there a GPIO that corresponds to /sys/class/graphics/fb0/blank? 
> Or... is
> there some kernel function I can call to control the LED's state? I
> imagine this is a generic kernel task, as the functions in pxafb.c are
> static entrypoints in a table.

Don't hit GPIO17 directly.  Use /sys/class/graphics/fb0/blank -- echo 
1 to that to turn off backlight and blank the screen; echo 0 to turn 
back on.  The FB driver will in turn toggle GPIO17 the correct way 
for you.  There is probably a linux console ESC sequence which will 
initiate the blanking (and cause the driver to twiddle the GPIO too) 
as well.

C

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