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>

diff --git a/drivers/hid/hid-rmi.c b/drivers/hid/hid-rmi.c
index e2a43a1..6e74eae 100644 (file)
--- 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;
 }