Input: synaptics - handle spurious release of trackstick buttons

The Fimware 8.1 has a bug in which the extra buttons are only sent when the
ExtBit is 1.  This should be fixed in a future FW update which should have
a bump of the minor version.

Cc: stable@vger.kernel.org
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

1 files changed, 25 insertions, 8 deletions

diff --git a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptics.c
index e78cc5578527..2f42a712f3e0 100644
--- a/drivers/input/mouse/synaptics.c
+++ b/drivers/input/mouse/synaptics.c
@@ -820,14 +820,36 @@ static void synaptics_report_semi_mt_data(struct input_dev *dev,
         }
 }
 
-static void synaptics_report_buttons(struct psmouse *psmouse,
-                                     const struct synaptics_hw_state *hw)
+static void synaptics_report_ext_buttons(struct psmouse *psmouse,
+                                         const struct synaptics_hw_state *hw)
 {
         struct input_dev *dev = psmouse->dev;
         struct synaptics_data *priv = psmouse->private;
         int ext_bits = (SYN_CAP_MULTI_BUTTON_NO(priv->ext_cap) + 1) >> 1;
         int i;
 
+        if (!SYN_CAP_MULTI_BUTTON_NO(priv->ext_cap))
+                return;
+
+        /* Bug in FW 8.1, buttons are reported only when ExtBit is 1 */
+        if (SYN_ID_FULL(priv->identity) == 0x801 &&
+            !((psmouse->packet[0] ^ psmouse->packet[3]) & 0x02))
+                return;
+
+        for (i = 0; i < ext_bits; i++) {
+                input_report_key(dev, BTN_0 + 2 * i,
+                        hw->ext_buttons & (1 << i));
+                input_report_key(dev, BTN_1 + 2 * i,
+                        hw->ext_buttons & (1 << (i + ext_bits)));
+        }
+}
+
+static void synaptics_report_buttons(struct psmouse *psmouse,
+                                     const struct synaptics_hw_state *hw)
+{
+        struct input_dev *dev = psmouse->dev;
+        struct synaptics_data *priv = psmouse->private;
+
         input_report_key(dev, BTN_LEFT, hw->left);
         input_report_key(dev, BTN_RIGHT, hw->right);
 
@@ -839,12 +861,7 @@ static void synaptics_report_buttons(struct psmouse *psmouse,
                 input_report_key(dev, BTN_BACK, hw->down);
         }
 
-        for (i = 0; i < ext_bits; i++) {
-                input_report_key(dev, BTN_0 + 2 * i,
-                                 hw->ext_buttons & (1 << i));
-                input_report_key(dev, BTN_1 + 2 * i,
-                                 hw->ext_buttons & (1 << (i + ext_bits)));
-        }
+        synaptics_report_ext_buttons(psmouse, hw);
 }
 
 static void synaptics_report_slot(struct input_dev *dev, int slot,