HID: rmi: disable dribble packets on Synaptics touchpads

When a finger is lifted from a Synaptics touchpad the firmware will continue
to interrupts for up to a second. These additional interrupts are know and
dribble interrupts. Since the data read from the touchpad does not change
the input subsystem only reports a single event. This makes the servicing of
dribble interrupts on Linux unnecessary. This patch simply disables dribble
interupts when configuring the touchpad.

Signed-off-by: Andrew Duggan <aduggan@synaptics.com>
Tested-by: Gabriele Mazzotta <gabriele.mzt@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 19 insertions, 0 deletions

diff --git a/drivers/hid/hid-rmi.c b/drivers/hid/hid-rmi.c
index e2a43a1d3aa3..6e74eae6b652 100644
--- a/drivers/hid/hid-rmi.c
+++ b/drivers/hid/hid-rmi.c
@@ -751,6 +751,7 @@ static int rmi_populate_f11(struct hid_device *hdev)
         bool has_gestures;
         bool has_rel;
         bool has_data40 = false;
+        bool has_dribble = false;
         unsigned x_size, y_size;
         u16 query_offset;
 
@@ -792,6 +793,14 @@ static int rmi_populate_f11(struct hid_device *hdev)
         has_rel = !!(buf[0] & BIT(3));
         has_gestures = !!(buf[0] & BIT(5));
 
+        ret = rmi_read(hdev, data->f11.query_base_addr + 5, buf);
+        if (ret) {
+                hid_err(hdev, "can not get absolute data sources: %d.\n", ret);
+                return ret;
+        }
+
+        has_dribble = !!(buf[0] & BIT(4));
+
         /*
          * At least 4 queries are guaranteed to be present in F11
          * +1 for query 5 which is present since absolute events are
@@ -908,6 +917,16 @@ static int rmi_populate_f11(struct hid_device *hdev)
         data->max_x = buf[6] | (buf[7] << 8);
         data->max_y = buf[8] | (buf[9] << 8);
 
+        if (has_dribble) {
+                buf[0] = buf[0] & ~BIT(6);
+                ret = rmi_write(hdev, data->f11.control_base_addr, buf);
+                if (ret) {
+                        hid_err(hdev, "can not write to control reg 0: %d.\n",
+                                ret);
+                        return ret;
+                }
+        }
+
         return 0;
 }