HID: hid-lg-g15: Add hw_brightness_changed support for the G510 keyboard

Add hw_brightness_changed support for the G510 keyboard, so that e.g.
GNOME will show an OSD notification when toggling the backlight on/off
with the button the keyboard.

Note that it is not possible to turn the backlight back on by writing
/sys/class/leds/.../brightness it can only be turned on by pressing
the button on the keyboard. To reflect this /sys/class/leds/.../brightness
will always report the last brightness value independent of the on/off
toggle built into the keyboard.

Signed-off-by: Hans de Goede <hansg@kernel.org>
Signed-off-by: Jiri Kosina <jkosina@suse.com>

diff --git a/drivers/hid/hid-lg-g15.c b/drivers/hid/hid-lg-g15.c
index 7b8df2d5b57f7f85a09312e6de104a2a8e597d48..1a88bc44ada4442495d82a333d16418435b69a57 100644 (file)
--- a/drivers/hid/hid-lg-g15.c
+++ b/drivers/hid/hid-lg-g15.c
@@ -26,6 +26,9 @@
 #define LG_G510_FEATURE_BACKLIGHT_RGB  0x05
 #define LG_G510_FEATURE_POWER_ON_RGB   0x06
 
+#define LG_G510_INPUT_MACRO_KEYS       0x03
+#define LG_G510_INPUT_KBD_BACKLIGHT    0x04
+
 #define LG_G13_INPUT_REPORT            0x01
 #define LG_G13_FEATURE_M_KEYS_LEDS     0x05
 #define LG_G13_FEATURE_BACKLIGHT_RGB   0x07
@@ -423,6 +426,20 @@ static int lg_g510_get_initial_led_brightness(struct lg_g15_data *g15, int i)
                g15->leds[i].brightness = 0;
        }
 
+       if (i)
+               return 0;
+
+       ret = hid_hw_raw_request(g15->hdev, LG_G510_INPUT_KBD_BACKLIGHT,
+                                g15->transfer_buf, 2,
+                                HID_INPUT_REPORT, HID_REQ_GET_REPORT);
+       if (ret != 2) {
+               /* This can happen when a KVM switch is used, so only warn. */
+               hid_warn(g15->hdev, "Error getting backlight state: %d\n", ret);
+               return 0;
+       }
+
+       g15->backlight_disabled = g15->transfer_buf[1] & 0x04;
+
        return 0;
 }
 
@@ -849,14 +866,24 @@ static int lg_g510_event(struct lg_g15_data *g15, u8 *data)
 
 static int lg_g510_leds_event(struct lg_g15_data *g15, u8 *data)
 {
+       struct lg_g15_led *g15_led = &g15->leds[LG_G15_KBD_BRIGHTNESS];
        bool backlight_disabled;
 
+       backlight_disabled = data[1] & 0x04;
+       if (backlight_disabled == g15->backlight_disabled)
+               return 0;
+
+       led_classdev_notify_brightness_hw_changed(
+               &g15_led->mcdev.led_cdev,
+               backlight_disabled ? 0 : g15_led->brightness);
+
+       g15->backlight_disabled = backlight_disabled;
+
        /*
         * The G510 ignores backlight updates when the backlight is turned off
         * through the light toggle button on the keyboard, to work around this
         * we queue a workitem to sync values when the backlight is turned on.
         */
-       backlight_disabled = data[1] & 0x04;
        if (!backlight_disabled)
                schedule_work(&g15->work);
 
@@ -892,9 +919,9 @@ static int lg_g15_raw_event(struct hid_device *hdev, struct hid_report *report,
                break;
        case LG_G510:
        case LG_G510_USB_AUDIO:
-               if (data[0] == 0x03 && size == 5)
+               if (data[0] == LG_G510_INPUT_MACRO_KEYS && size == 5)
                        return lg_g510_event(g15, data);
-               if (data[0] == 0x04 && size == 2)
+               if (data[0] == LG_G510_INPUT_KBD_BACKLIGHT && size == 2)
                        return lg_g510_leds_event(g15, data);
                break;
        }
@@ -933,6 +960,8 @@ static void lg_g15_setup_led_rgb(struct lg_g15_data *g15, int index)
                        lg_g510_kbd_led_set;
                gled->mcdev.led_cdev.brightness_get =
                        lg_g510_kbd_led_get;
+               if (index == LG_G15_KBD_BRIGHTNESS)
+                       g15->leds[index].mcdev.led_cdev.flags = LED_BRIGHT_HW_CHANGED;
        }
        gled->mcdev.led_cdev.max_brightness = 255;
        gled->mcdev.num_colors = 3;