platform/x86: asus-wmi: Do not report brightness up/down keys when also reported by acpi_video

For a long time now the acpi_video driver reports evdev brightness up/down
key events for the brightness hotkeys on most (non ancient) laptops.

asus-wmi also reports evdev brightness up/down key events for these
keys leading to each press being reported twice and e.g. GNOME increasing
the brightness by 2 steps instead of 1 step.

Use the acpi_video_handles_brightness_key_presses() helper to detect if
acpi_video is reporting brightness key-presses and if it is then don't
report the same events also from the asus-wmi driver.

Note there is a chance that this may lead to regressions where
the brightness hotkeys stop working because they are not actually
reported by the acpi_video driver. Unfortunately the only way to
find out if this is a problem is to try.

To at least avoid regressions on old hw using the eeepc-wmi driver,
implement this as a key filter in asus-nb-wmi so that the eeepc-wmi
driver is not affected.

Reported-by: James John <me@donjajo.com>
Closes: https://lore.kernel.org/platform-driver-x86/a2c441fe-457e-44cf-a146-0ecd86b037cf@donjajo.com/
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20231021094841.7419-1-hdegoede@redhat.com
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>

Author: jwrdegoede

drivers/platform/x86/asus-nb-wmi.c

@@ -16,6 +16,8 @@
 #include <linux/dmi.h>
 #include <linux/i8042.h>
 
+#include <acpi/video.h>
+
 #include "asus-wmi.h"
 
 #define	ASUS_NB_WMI_FILE	"asus-nb-wmi"
@@ -603,6 +605,19 @@ static const struct key_entry asus_nb_wmi_keymap[] = {
 	{ KE_END, 0},
 };
 
+static void asus_nb_wmi_key_filter(struct asus_wmi_driver *asus_wmi, int *code,
+				   unsigned int *value, bool *autorelease)
+{
+	switch (*code) {
+	case ASUS_WMI_BRN_DOWN:
+	case ASUS_WMI_BRN_UP:
+		if (acpi_video_handles_brightness_key_presses())
+			*code = ASUS_WMI_KEY_IGNORE;
+
+		break;
+	}
+}
+
 static struct asus_wmi_driver asus_nb_wmi_driver = {
 	.name = ASUS_NB_WMI_FILE,
 	.owner = THIS_MODULE,
@@ -611,6 +626,7 @@ static struct asus_wmi_driver asus_nb_wmi_driver = {
 	.input_name = "Asus WMI hotkeys",
 	.input_phys = ASUS_NB_WMI_FILE "/input0",
 	.detect_quirks = asus_nb_wmi_quirks,
+	.key_filter = asus_nb_wmi_key_filter,
 };