Input: psmouse - fix Synaptics detection when protocol is disabled

For configurations where Synaptics hardware is present but the Synaptics
extensions support is not compiled in, the mouse is reprobed and a new
device is allocated on every suspend/resume.

During probe, psmouse_switch_protocol() calls psmouse_extensions() with
set_properties=1. This calls the dummy synaptics_init() which returns an
error code, instructing us not to use the synaptics extensions.

During resume, psmouse_reconnect() calls psmouse_extensions() with
set_properties=0, in which case call to synaptics_init() is bypassed and
PSMOUSE_SYNAPTICS is returned. Since the result is different from previous
attempt psmouse_reconnect() fails and full re-probe happens.

Fix this by tweaking the set_properties=0 codepath in psmouse_extensions()
to be more careful about offering PSMOUSE_SYNAPTICS extensions.

Signed-off-by: Daniel Drake <dsd@laptop.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 8 insertions, 1 deletions

diff --git a/drivers/input/mouse/psmouse-base.c b/drivers/input/mouse/psmouse-base.c
index d59e18b24ede..cabf4e1caacc 100644
--- a/drivers/input/mouse/psmouse-base.c
+++ b/drivers/input/mouse/psmouse-base.c
@@ -627,8 +627,15 @@ static int psmouse_extensions(struct psmouse *psmouse,
                 synaptics_hardware = true;
 
                 if (max_proto > PSMOUSE_IMEX) {
-                        if (!set_properties || synaptics_init(psmouse) == 0)
+/*
+ * Try activating protocol, but check if support is enabled first, since
+ * we try detecting Synaptics even when protocol is disabled.
+ */
+                        if (synaptics_supported() &&
+                            (!set_properties || synaptics_init(psmouse) == 0)) {
                                 return PSMOUSE_SYNAPTICS;
+                        }
+
 /*
  * Some Synaptics touchpads can emulate extended protocols (like IMPS/2).
  * Unfortunately Logitech/Genius probes confuse some firmware versions so