If the driver has no fb_blank hook, then the generic method is to clear the
screen and then disallow writes to the framebuffer.  However, if the
console is leaving graphics mode (KD_GRAPHICS), it would update the screen
first, then unblank.  However, since writes to the framebuffers are
disallowed, the update failes, and upon unblank, the screen is left empty
except for the flashing cursor.  (This happens, for example when switching
from X to console).

The fix is to allow writes to the framebuffer even if the console is
blanked.  To imitate a blank screen, the get_color() function will return
the attributes of the erase character (black on black) if the console is
blanked and if the driver has no fb_blank hook.

I think this fixes the rest of the major bugs in the blanking code.  
Signed-off-by: Antonino Daplas <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>