Why is LCD display cleared after 10 minutes?

Ron Olson

Other Parts Discussed in Thread: AM3517

We're running linux from TI's TI_Android_GingerBread_2_3_4Sources release, on an AM3517evm. This question pertains to a non-android build we do using configuration am3517_evm_defconfig.

We've disabled TI's kernel boot progress screen on the LCD display. So, during the kernel boot, the penguin displays on the LCD. But, after 10 minutes, the penguin disappears, simultaneous with a call being made to function sharp_lq_bl_update_status() in our LCD driver (panel-sharp-lq043t1dg01). By the way, this function wasn't in the original TI version of this driver, but I ported it over from a driver that had backlight support (panel-sharp-ls037v7dw01) and added the logs.

I want the penguin to remain on the display. So, I want this 10 minute timer to keep from firing, or perhaps to stretch it out to a huge number if that's easier.

Can anyone tell me where the value for this 10 minute timer is defined, or where the timer is actually set?

Thanks,
Ron

over 12 years ago

0 Doug Brown over 12 years ago

Intellectual 320 points

Hi Ron,

I believe what you're seeing is caused by a default Linux behavior that puts the framebuffer into sleep mode after 10 minutes--I've also seen it on other non-TI systems. The best page I've found with info about how to control the framebuffer is here.

From that page, to disable the sleep timer, type:

# echo -e '\033[9;0]' > /dev/tty1

(assuming that your framebuffer console is /dev/tty1)

Although I haven't tried this second approach before, it appears you can also use the consoleblank kernel boot parameter.

0 Prakash PM over 12 years ago in reply to Doug Brown

TI__Intellectual 1275 points

HI,

Below solutions works:

To disable console blanking altogether: append consoleblank=0 to kernel bootargs.
wakeup from blanked console $echo 0 > /sys/class/graphics/fb0/blank.

Thanks,

Prakash

0 Ron Olson over 12 years ago in reply to Doug Brown

Intellectual 680 points

Doug and Prakash,

Thank you for both of your responses. They provide me with the information I needed.

I am using the approach of turning off the sleep timer by writing the special sequence to the framebuffer tty device, and that works fine.

Regards,
Ron

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Why is LCD display cleared after 10 minutes?