[PATCH] asus-wmi: filter buggy scan codes on ASUS Q500A

[Oleksij Rempel <linux@rempel-privat.de>]

Some revision of ASUS Q500A series have keyboard related
issue which is reproducible only if Windows with installed ASUS
tools was ever started.
In this case the Linux side will have blocked keyboard or
report wrong or incomplete hotkey events.
To make Linux work properly again complete power down
(unplug power supply and remove battery) should be made.

Linux/atkbd after clean start will get fallowing code on VOLUME_UP
key: {0xe0, 0x30, 0xe0, 0xb0}. After Windows, same key will generate this
codes: {0xe1, 0x23, 0xe0, 0x30, 0xe0, 0xb0}. As result atkdb will
be confused by buggy codes.

This patch is filtering this buggy code out.

https://bugzilla.kernel.org/show_bug.cgi?id=119391

Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
Cc: Alex Henrie <alexhenrie24@gmail.com>
Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: Corentin Chary <corentin.chary@gmail.com>
Cc: Darren Hart <dvhart@infradead.org>
Cc: acpi4asus-user@lists.sourceforge.net
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/platform/x86/asus-nb-wmi.c | 45 ++++++++++++++++++++++++++++++++++++++
 drivers/platform/x86/asus-wmi.h    |  4 ++++
 2 files changed, 49 insertions(+)

diff --git a/drivers/platform/x86/asus-nb-wmi.c b/drivers/platform/x86/asus-nb-wmi.c
index adecc1c..787da83 100644
--- a/drivers/platform/x86/asus-nb-wmi.c
+++ b/drivers/platform/x86/asus-nb-wmi.c
@@ -27,6 +27,7 @@
 #include <linux/input/sparse-keymap.h>
 #include <linux/fb.h>
 #include <linux/dmi.h>
+#include <linux/i8042.h>
 
 #include "asus-wmi.h"
 
@@ -55,10 +56,35 @@ MODULE_PARM_DESC(wapf, "WAPF value");
 
 static struct quirk_entry *quirks;
 
+static bool asus_q500a_i8042_filter(unsigned char data, unsigned char str,
+			      struct serio *port)
+{
+	static bool extended;
+	bool ret = false;
+
+
+	if (str & I8042_STR_AUXDATA)
+		return false;
+
+	if (unlikely(data == 0xe1)) {
+		extended = true;
+		ret = true;
+	} else if (unlikely(extended)) {
+		extended = false;
+		ret = true;
+	}
+
+	return ret;
+}
+
 static struct quirk_entry quirk_asus_unknown = {
 	.wapf = 0,
 };
 
+static struct quirk_entry quirk_asus_q500a = {
+	.i8042_filter = asus_q500a_i8042_filter,
+};
+
 /*
  * For those machines that need software to control bt/wifi status
  * and can't adjust brightness through ACPI interface
@@ -96,6 +122,15 @@ static int dmi_matched(const struct dmi_system_id *dmi)
 static const struct dmi_system_id asus_quirks[] = {
 	{
 		.callback = dmi_matched,
+		.ident = "ASUSTeK COMPUTER INC. Q500A",
+		.matches = {
+			DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK COMPUTER INC."),
+			DMI_MATCH(DMI_PRODUCT_NAME, "Q500A"),
+		},
+		.driver_data = &quirk_asus_q500a,
+	},
+	{
+		.callback = dmi_matched,
 		.ident = "ASUSTeK COMPUTER INC. U32U",
 		.matches = {
 			DMI_MATCH(DMI_SYS_VENDOR, "ASUSTeK Computer Inc."),
@@ -356,6 +391,8 @@ static const struct dmi_system_id asus_quirks[] = {
 
 static void asus_nb_wmi_quirks(struct asus_wmi_driver *driver)
 {
+	int ret;
+
 	quirks = &quirk_asus_unknown;
 	dmi_check_system(asus_quirks);
 
@@ -367,6 +404,14 @@ static void asus_nb_wmi_quirks(struct asus_wmi_driver *driver)
 		quirks->wapf = wapf;
 	else
 		wapf = quirks->wapf;
+
+	if (quirks->i8042_filter) {
+		ret = i8042_install_filter(quirks->i8042_filter);
+		if (ret) {
+			pr_warn("Unable to install key filter\n");
+		}
+		pr_info("Using i8042 filter function for receiving events\n");
+	}
 }
 
 static const struct key_entry asus_nb_wmi_keymap[] = {
diff --git a/drivers/platform/x86/asus-wmi.h b/drivers/platform/x86/asus-wmi.h
index 5de1df5..dd2e6cc 100644
--- a/drivers/platform/x86/asus-wmi.h
+++ b/drivers/platform/x86/asus-wmi.h
@@ -28,6 +28,7 @@
 #define _ASUS_WMI_H_
 
 #include <linux/platform_device.h>
+#include <linux/i8042.h>
 
 #define ASUS_WMI_KEY_IGNORE (-1)
 #define ASUS_WMI_BRN_DOWN	0x20
@@ -51,6 +52,9 @@ struct quirk_entry {
 	 * and let the ACPI interrupt to send out the key event.
 	 */
 	int no_display_toggle;
+
+	bool (*i8042_filter)(unsigned char data, unsigned char str,
+			     struct serio *serio);
 };
 
 struct asus_wmi_driver {
-- 
2.7.4