Linux disable framebuffer auto blank by uboot bootargs

Document created by Biyong Sun Employee on Mar 13, 2014
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Very often, customers need to disable the framebuffer auto blank.

There are several ways to do so.

 

Modify the code in drivers/tty/vt/vt.c or remove the  “CONFIG_VT_CONSOLE” from the kernel configuration.

All these work, but inconvenient.

 

Review the code following:

 

static int vesa_blank_mode; /* 0:none 1:suspendV 2:suspendH 3:powerdown */

static int vesa_off_interval;

static int blankinterval = 10*60;

core_param(consoleblank, blankinterval, int, 0444);

 

The blank is controlled by blankinterval, which can be set with the name consoleblank.

And the consoleblank is a "core_param".

core_param in linux can be recognized by kernel. Also can be passed to kernel command line from uboot with bootargs.

we could add this to the bootargs

 

that the framebuffer will not go blank: consoleblank=0

 

Example(verified with imx6 L3.0.35_4.1.0_130816):

setenv bootargs_mmc 'setenv bootargs ${bootargs} root=/dev/mmcblk1p1 rootfstype=ext4 rootwait video=mxcfb0:dev=hdmi,1920x1080M@60,if=RGB24,bpp=32 fbmem=28M consoleblank=0'

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