Subject: + drivers-video-backlight-backlightc-remove-backlight-sysfs-uevent.patch added to -mm tree
To: kyungmin.park@xxxxxxxxxxx,hmh@xxxxxxxxxx,ibm-acpi@xxxxxxxxxx,jg1.han@xxxxxxxxxxx,kay.sievers@xxxxxxxx,mjg59@xxxxxxxxxxxxx,rpurdie@xxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Mon, 16 Dec 2013 11:55:56 -0800
The patch titled
Subject: drivers/video/backlight/backlight.c: remove backlight sysfs uevent
has been added to the -mm tree. Its filename is
drivers-video-backlight-backlightc-remove-backlight-sysfs-uevent.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/drivers-video-backlight-backlightc-remove-backlight-sysfs-uevent.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/drivers-video-backlight-backlightc-remove-backlight-sysfs-uevent.patch
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------------------------------------------------------
From: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
Subject: drivers/video/backlight/backlight.c: remove backlight sysfs uevent
Most mobile phones have Ambient Light Sensors and it changes brightness
according to the lux. It means it changes backlight brightness frequently
by just writing sysfs node, so it generates uevent.
Usually there's no user to use this backlight changes. But it forks udev
worker threads and it takes about 5ms. The main problem is that it hurts
other process activities. so remove it.
Kay said
"Uevents are for the major, low-frequent, global device state-changes,
not for carrying-out any sort of measurement data. Subsystems which
need that should use other facilities like poll()-able sysfs file or
any other subscription-based, client-tracking interface which does not
cause overhead if it isn't used. Uevents are not the right thing to
use here, and upstream udev should not paper-over broken kernel
subsystems."
Signed-off-by: Kyungmin Park <kyungmin.park@xxxxxxxxxxx>
Cc: Henrique de Moraes Holschuh <hmh@xxxxxxxxxx>
Cc: Matthew Garrett <mjg59@xxxxxxxxxxxxx>
Cc: Kay Sievers <kay.sievers@xxxxxxxx>
Acked-by: Jingoo Han <jg1.han@xxxxxxxxxxx>
Cc: Henrique de Moraes Holschuh <ibm-acpi@xxxxxxxxxx>
Cc: Richard Purdie <rpurdie@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/video/backlight/backlight.c | 2 --
1 file changed, 2 deletions(-)
diff -puN drivers/video/backlight/backlight.c~drivers-video-backlight-backlightc-remove-backlight-sysfs-uevent drivers/video/backlight/backlight.c
--- a/drivers/video/backlight/backlight.c~drivers-video-backlight-backlightc-remove-backlight-sysfs-uevent
+++ a/drivers/video/backlight/backlight.c
@@ -175,8 +175,6 @@ static ssize_t brightness_store(struct d
}
mutex_unlock(&bd->ops_lock);
- backlight_generate_event(bd, BACKLIGHT_UPDATE_SYSFS);
-
return rc;
}
static DEVICE_ATTR_RW(brightness);
_
Patches currently in -mm which might be from kyungmin.park@xxxxxxxxxxx are
origin.patch
rtc-s5m-fix-unsuccesful-irq-request-during-probe.patch
rtc-s5m-limit-endless-loop-waiting-for-register-update.patch
rtc-s5m-enable-irq-wake-during-suspend.patch
mfd-rtc-s5m-fix-register-updating-by-adding-regmap-for-rtc.patch
drivers-video-backlight-backlightc-remove-backlight-sysfs-uevent.patch
linux-next.patch
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