Re: [PATCH] platform/x86: dell-laptop: Filter out spurious keyboard backlight change events

From: Andy Shevchenko
Date: Fri Jan 05 2018 - 05:40:13 EST


On Thu, Jan 4, 2018 at 10:52 AM, Hans de Goede <hdegoede@xxxxxxxxxx> wrote:
> On some Dell XPS models WMI events of type 0x0000 reporting a keycode of
> 0xe00c get reported when the brightness of the LCD panel changes.
>
> This leads to us reporting false-positive kbd_led change events to
> userspace which in turn leads to the kbd backlight OSD showing when it
> should not.
>
> We already read the current keyboard backlight brightness value when
> reporting events because the led_classdev_notify_brightness_hw_changed
> API requires this. Compare this value to the last known value and filter
> out duplicate events, fixing this.
>
> Note the fixed issue is esp. a problem on XPS models with an ambient light
> sensor and automatic brightness adjustments turned on, this causes the kbd
> backlight OSD to show all the time there.
>

Should it have Fixes tag?

Pali, any comment on this?

> BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1514969
> Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> ---
> drivers/platform/x86/dell-laptop.c | 24 ++++++++++++++++++++++--
> 1 file changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/platform/x86/dell-laptop.c b/drivers/platform/x86/dell-laptop.c
> index cd4725e7e0b5..2ef3297a9efc 100644
> --- a/drivers/platform/x86/dell-laptop.c
> +++ b/drivers/platform/x86/dell-laptop.c
> @@ -1133,6 +1133,7 @@ static u8 kbd_previous_mode_bit;
>
> static bool kbd_led_present;
> static DEFINE_MUTEX(kbd_led_mutex);
> +static enum led_brightness kbd_led_level;
>
> /*
> * NOTE: there are three ways to set the keyboard backlight level.
> @@ -1947,6 +1948,7 @@ static enum led_brightness kbd_led_level_get(struct led_classdev *led_cdev)
> static int kbd_led_level_set(struct led_classdev *led_cdev,
> enum led_brightness value)
> {
> + enum led_brightness new_value = value;
> struct kbd_state state;
> struct kbd_state new_state;
> u16 num;
> @@ -1976,6 +1978,9 @@ static int kbd_led_level_set(struct led_classdev *led_cdev,
> }
>
> out:
> + if (ret == 0)
> + kbd_led_level = new_value;
> +
> mutex_unlock(&kbd_led_mutex);
> return ret;
> }
> @@ -2003,6 +2008,9 @@ static int __init kbd_led_init(struct device *dev)
> if (kbd_led.max_brightness)
> kbd_led.max_brightness--;
> }
> +
> + kbd_led_level = kbd_led_level_get(NULL);
> +
> ret = led_classdev_register(dev, &kbd_led);
> if (ret)
> kbd_led_present = false;
> @@ -2027,13 +2035,25 @@ static void kbd_led_exit(void)
> static int dell_laptop_notifier_call(struct notifier_block *nb,
> unsigned long action, void *data)
> {
> + bool changed = false;
> + enum led_brightness new_kbd_led_level;
> +
> switch (action) {
> case DELL_LAPTOP_KBD_BACKLIGHT_BRIGHTNESS_CHANGED:
> if (!kbd_led_present)
> break;
>
> - led_classdev_notify_brightness_hw_changed(&kbd_led,
> - kbd_led_level_get(&kbd_led));
> + mutex_lock(&kbd_led_mutex);
> + new_kbd_led_level = kbd_led_level_get(&kbd_led);
> + if (kbd_led_level != new_kbd_led_level) {
> + kbd_led_level = new_kbd_led_level;
> + changed = true;
> + }
> + mutex_unlock(&kbd_led_mutex);
> +
> + if (changed)
> + led_classdev_notify_brightness_hw_changed(&kbd_led,
> + kbd_led_level);
> break;
> }
>
> --
> 2.14.3
>



--
With Best Regards,
Andy Shevchenko