[PATCH AUTOSEL for 4.4 025/167] Input: elantech - force relative mode on a certain module

Sasha Levin
2018-03-19T17:31:21Z

From: KT Liao <kt.liao@emc.com.tw>

[ 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>
---
drivers/input/mouse/elantech.c | 11 +++++++++++
1 file changed, 11 insertions(+)

diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
index 51b96e9bf793..06ea28e5d7b4 100644
--- 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");
--
2.14.1