• Liu Ying's avatar
    backlight: update bd state & fb_blank properties when necessary · a55944ca
    Liu Ying authored
    We don't have to update the state and fb_blank properties of a backlight
    device every time a blanking or unblanking event comes because they may
    have already been what we want.  Another thought is that one backlight
    device may be shared by multiple framebuffers.  The backlight driver
    should take the backlight device as a resource shared by all the
    associated framebuffers.
    
    This patch adds some logic to record each framebuffer's backlight usage
    to determine the backlight device use count and whether the two
    properties should be updated or not.  To be more specific, only one
    unblank operation on a certain blanked framebuffer may increase the
    backlight device's use count by one, while one blank operation on a
    certain unblanked framebuffer may decrease the use count by one, because
    the userspace is likely to unblank an unblanked framebuffer or blank a
    blanked framebuffer.
    Signed-off-by: default avatarLiu Ying <Ying.Liu@freescale.com>
    Cc: Jingoo Han <jg1.han@samsung.com>
    Cc: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
    Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
    Cc: Jani Nikula <jani.nikula@linux.intel.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    a55944ca
backlight.c 14.4 KB