Linux Device Drivers Development

Screen blanking

The fb_ops->fb_blank hook is a hardware-specific hook, responsible for screen blanking. Its prototype is as follows:

int (*fb_blank)(int blank_mode, struct fb_info *info) 

The blank_mode parameter is always one of the following values:

enum { 
   /* screen: unblanked, hsync: on,  vsync: on */ 
   FB_BLANK_UNBLANK       = VESA_NO_BLANKING, 
 
   /* screen: blanked,   hsync: on,  vsync: on */ 
   FB_BLANK_NORMAL        = VESA_NO_BLANKING + 1, 
 
   /* screen: blanked,   hsync: on,  vsync: off */ 
   FB_BLANK_VSYNC_SUSPEND = VESA_VSYNC_SUSPEND + 1, 
 
   /* screen: blanked,   hsync: off, vsync: on */ 
   FB_BLANK_HSYNC_SUSPEND = VESA_HSYNC_SUSPEND + 1, 
 
   /* screen: blanked,   hsync: off, vsync: off */ 
   FB_BLANK_POWERDOWN     = VESA_POWERDOWN + 1 
}; 

The usual way of doing a blank display is to ...