Please ignore it. strange mail system. After feedback from previous mail, I'll re-send it.
Thank you, Kyungmin Park On Tue, Nov 12, 2013 at 9:44 AM, Kyungmin Park <kmp...@infradead.org> 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> > --- > diff --git a/drivers/video/backlight/backlight.c > b/drivers/video/backlight/backlight.c > index 94a403a..441272d 100644 > --- a/drivers/video/backlight/backlight.c > +++ b/drivers/video/backlight/backlight.c > @@ -88,9 +88,6 @@ static void backlight_generate_event(struct > backlight_device *bd, > char *envp[2]; > > switch (reason) { > - case BACKLIGHT_UPDATE_SYSFS: > - envp[0] = "SOURCE=sysfs"; > - break; > case BACKLIGHT_UPDATE_HOTKEY: > envp[0] = "SOURCE=hotkey"; > break; > @@ -172,8 +169,6 @@ 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); > diff --git a/include/linux/backlight.h b/include/linux/backlight.h > index 53b7794..d2a27dd 100644 > --- a/include/linux/backlight.h > +++ b/include/linux/backlight.h > @@ -29,7 +29,6 @@ > > enum backlight_update_reason { > BACKLIGHT_UPDATE_HOTKEY, > - BACKLIGHT_UPDATE_SYSFS, > }; > > enum backlight_type { > -- > 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/ -- 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/