platform/x86: panasonic-laptop: don't report duplicate brightness key-presses

The brightness key-presses might also get reported by the ACPI video bus,
check for this and in this case don't report the presses to avoid reporting
2 presses for a single key-press.

Fixes: ed83c917 ("platform/x86: panasonic-laptop: Resolve hotkey double trigger bug")
Reported-and-tested-by: Stefan Seyfried <seife+kernel@b1-systems.com>
Reported-and-tested-by: Kenneth Chan <kenneth.t.chan@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220624112340.10130-6-hdegoede@redhat.com

drivers/platform/x86/Kconfig

@@ -918,6 +918,7 @@ config PANASONIC_LAPTOP
 	tristate "Panasonic Laptop Extras"
 	depends on INPUT && ACPI
 	depends on BACKLIGHT_CLASS_DEVICE
+	depends on ACPI_VIDEO=n || ACPI_VIDEO
 	select INPUT_SPARSEKMAP
 	help
 	  This driver adds support for access to backlight control and hotkeys

drivers/platform/x86/panasonic-laptop.c

@@ -132,6 +132,7 @@
 #include <linux/slab.h>
 #include <linux/types.h>
 #include <linux/uaccess.h>
+#include <acpi/video.h>
 
 MODULE_AUTHOR("Hiroshi Miura <miura@da-cha.org>");
 MODULE_AUTHOR("David Bronaugh <dbronaugh@linuxboxen.org>");
@@ -783,6 +784,13 @@ static void acpi_pcc_generate_keyinput(struct pcc_acpi *pcc)
 					key, 0x80, false);
 	}
 
+	/*
+	 * Don't report brightness key-presses if they are also reported
+	 * by the ACPI video bus.
+	 */
+	if ((key == 1 || key == 2) && acpi_video_handles_brightness_key_presses())
+		return;
+
 	if (!sparse_keymap_report_event(hotk_input_dev, key, updown, false))
 		pr_err("Unknown hotkey event: 0x%04llx\n", result);
 }