Input: cypress_ps2 - fix trackpadi found in Dell XPS12

Avoid firmware glitch in Cypress PS/2 Trackpad firmware version 11
(as observed in Dell XPS12) which prevents driver from recognizing
the trackpad.

BugLink: http://launchpad.net/bugs/1103594

Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Cc: Dudley Du <dudl@cypress.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

1 files changed, 13 insertions, 6 deletions

diff --git a/drivers/input/mouse/cypress_ps2.c b/drivers/input/mouse/cypress_ps2.c
index 1673dc6c8092..f51765fff054 100644
--- a/drivers/input/mouse/cypress_ps2.c
+++ b/drivers/input/mouse/cypress_ps2.c
@@ -236,6 +236,13 @@ static int cypress_read_fw_version(struct psmouse *psmouse)
         cytp->fw_version = param[2] & FW_VERSION_MASX;
         cytp->tp_metrics_supported = (param[2] & TP_METRICS_MASK) ? 1 : 0;
 
+        /*
+         * Trackpad fw_version 11 (in Dell XPS12) yields a bogus response to
+         * CYTP_CMD_READ_TP_METRICS so do not try to use it. LP: #1103594.
+         */
+        if (cytp->fw_version >= 11)
+                cytp->tp_metrics_supported = 0;
+
         psmouse_dbg(psmouse, "cytp->fw_version = %d\n", cytp->fw_version);
         psmouse_dbg(psmouse, "cytp->tp_metrics_supported = %d\n",
                  cytp->tp_metrics_supported);
@@ -258,6 +265,9 @@ static int cypress_read_tp_metrics(struct psmouse *psmouse)
         cytp->tp_res_x = cytp->tp_max_abs_x / cytp->tp_width;
         cytp->tp_res_y = cytp->tp_max_abs_y / cytp->tp_high;
 
+        if (!cytp->tp_metrics_supported)
+                return 0;
+
         memset(param, 0, sizeof(param));
         if (cypress_send_ext_cmd(psmouse, CYTP_CMD_READ_TP_METRICS, param) == 0) {
                 /* Update trackpad parameters. */
@@ -315,18 +325,15 @@ static int cypress_read_tp_metrics(struct psmouse *psmouse)
 
 static int cypress_query_hardware(struct psmouse *psmouse)
 {
-        struct cytp_data *cytp = psmouse->private;
         int ret;
 
         ret = cypress_read_fw_version(psmouse);
         if (ret)
                 return ret;
 
-        if (cytp->tp_metrics_supported) {
-                ret = cypress_read_tp_metrics(psmouse);
-                if (ret)
-                        return ret;
-        }
+        ret = cypress_read_tp_metrics(psmouse);
+        if (ret)
+                return ret;
 
         return 0;
 }