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authorLiu Ying <Ying.Liu@freescale.com>2014-04-03 14:48:55 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-04-03 16:21:09 -0700
commit8c16f3303c3410d4af19c8bdc73b74c83c042e87 (patch)
tree7bf79dfe1848d2f7d4587eec737bc5f5c0dbe4fd /drivers
parenta55944ca82d287ca099ca90413af857af9086773 (diff)
backlight: update backlight status when necessary
We don't have to update a backlight status every time a blanking or unblanking event comes because the backlight status may have already been what we want. Another thought is that one backlight device may be shared by multiple framebuffers. We don't hope blanking one of the framebuffers may turn the backlight off for all the other framebuffers, since they are likely being active to display something. This patch makes the backlight status be updated only when the relevant backlight device's use count changes from zero to one or from one to zero. Signed-off-by: Liu 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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/video/backlight/backlight.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index efc9a2da918..27d3cf255e7 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -34,7 +34,7 @@ static const char *const backlight_types[] = {
defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE))
/* This callback gets called when something important happens inside a
* framebuffer driver. We're looking if that important event is blanking,
- * and if it is, we're switching backlight power as well ...
+ * and if it is and necessary, we're switching backlight power as well ...
*/
static int fb_notifier_callback(struct notifier_block *self,
unsigned long event, void *data)
@@ -60,6 +60,7 @@ static int fb_notifier_callback(struct notifier_block *self,
if (!bd->use_count++) {
bd->props.state &= ~BL_CORE_FBBLANK;
bd->props.fb_blank = FB_BLANK_UNBLANK;
+ backlight_update_status(bd);
}
} else if (fb_blank != FB_BLANK_UNBLANK &&
bd->fb_bl_on[node]) {
@@ -67,9 +68,9 @@ static int fb_notifier_callback(struct notifier_block *self,
if (!(--bd->use_count)) {
bd->props.state |= BL_CORE_FBBLANK;
bd->props.fb_blank = fb_blank;
+ backlight_update_status(bd);
}
}
- backlight_update_status(bd);
}
mutex_unlock(&bd->ops_lock);
return 0;