Input: elantech - force relative mode on a certain module

[ Upstream commit d899520b0431e70279bfb5066ecb6dc91d0b7072 ]

One of Elan modules with sample version is 0x74 and hw_version is 0x03 has
a bug in absolute mode implementation, so let it run in default PS/2
relative mode.

Signed-off-by: KT Liao <kt.liao@emc.com.tw>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
index 51b96e9..06ea28e 100644 (file)
--- a/drivers/input/mouse/elantech.c
+++ b/drivers/input/mouse/elantech.c
@@ -1715,6 +1715,17 @@ int elantech_init(struct psmouse *psmouse)
                             etd->samples[0], etd->samples[1], etd->samples[2]);
        }
 
+       if (etd->samples[1] == 0x74 && etd->hw_version == 0x03) {
+               /*
+                * This module has a bug which makes absolute mode
+                * unusable, so let's abort so we'll be using standard
+                * PS/2 protocol.
+                */
+               psmouse_info(psmouse,
+                            "absolute mode broken, forcing standard PS/2 protocol\n");
+               goto init_fail;
+       }
+
        if (elantech_set_absolute_mode(psmouse)) {
                psmouse_err(psmouse,
                            "failed to put touchpad into absolute mode.\n");