On Tuesday, November 12, 2013 12:39 PM, Kyungmin Park wrote: > > From: Kyungmin Park <kyungmin.p...@samsung.com> > > The most mobile phones have Ambient Light Sensors and it changes brightness > according 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.p...@samsung.com>
Acked-by: Jingoo Han <jg1....@samsung.com> Best regards, Jingoo Han > --- > v1: there's still user to use BACKLIGHT_UPDATE_SYSFS. so just remove store > sysfs node uevent > > --- > diff --git a/drivers/video/backlight/backlight.c > b/drivers/video/backlight/backlight.c > index 94a403a..292cf99 100644 > --- a/drivers/video/backlight/backlight.c > +++ b/drivers/video/backlight/backlight.c > @@ -172,8 +172,6 @@ static ssize_t brightness_store(struct device *dev, > } > mutex_unlock(&bd->ops_lock); > > - backlight_generate_event(bd, BACKLIGHT_UPDATE_SYSFS); > - > return rc; > } > static DEVICE_ATTR_RW(brightness); -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
