platform/x86: asus-wmi: Filter buggy scan codes on ASUS Q500A

Some revisions of the ASUS Q500A series have a keyboard related
issue which is reproducible only after Windows with installed ASUS
tools is started.

In this case the Linux side will have a blocked keyboard or
report incorrect or incomplete hotkey events.

To make Linux work properly again, a complete power down
(unplug power supply and remove battery) is needed.

Linux/atkbd after a clean start will get the following code on VOLUME_UP
key: {0xe0, 0x30, 0xe0, 0xb0}. After Windows, the 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: acpi4asus-user@lists.sourceforge.net
Cc: platform-driver-x86@vger.kernel.org
Cc: linux-kernel@vger.kernel.org

[dvhart: Add return after pr_warn to avoid false confirmation of filter]

Signed-off-by: Darren Hart <dvhart@linux.intel.com>

2 files changed, 49 insertions, 0 deletions

diff --git a/drivers/platform/x86/asus-nb-wmi.c b/drivers/platform/x86/asus-nb-wmi.c
index f4a60e75cd8a..26e4cbc34db8 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 +56,34 @@ 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
@@ -100,6 +125,15 @@ 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."),
@@ -369,6 +403,8 @@ 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);
 
@@ -380,6 +416,15 @@ 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");
+                        return;
+                }
+                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 5e220411056d..0e19014e9f54 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
@@ -52,6 +53,9 @@ 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 {