[PATCH] Input - synaptics: fix resolution for manually provided min/max

[Benjamin Tissoires <benjamin.tissoires@redhat.com>]

commit 421e08c41fda fixed the reported min/max for the X and Y axis,
but unfortunately, it broke the resolution of those same axis.

On the t540p, the resolution is the same regarding X and Y. It is not
a problem for xf86-input-synaptics because this driver is only interested
in the ratio between X and Y.
Unfortunately, xf86-input-cmt uses directly the resolution, and having a
null resolution leads to some divide by 0 errors, which are translated by
-infinity in the resulting coordinates.

Reported-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc: stable@vger.kernel.org
---

Hi Dmitry,

in the original submission, the test for the quirk was at the end of the
synaptics_resolution() function. However, there was a mixmatch with the config
in this original submission and you had to change the patch slightly.
Unfortunately, this change created this bug which was hard to notice, which is
why it comes that late in the cycle (and also because we are trying to find out
if xf86-input-cmt could replace xf86-input-synaptics).

Anyway, as mentioned in the commit message, this will not harm a big majority
of users, because only those using ChromeOS will be impacted (not sure they
have the Lenovo 40 series in their kernel either).

Again, it's your call to leave or not the stable@ tag, but given that all we
put regarding those crappy devices are tagged as such, I put it there also.

Cheers,
Benjamin

 drivers/input/mouse/synaptics.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptics.c
index c5ec703..9cff1f8 100644
--- a/drivers/input/mouse/synaptics.c
+++ b/drivers/input/mouse/synaptics.c
@@ -347,15 +347,6 @@ static int synaptics_resolution(struct psmouse *psmouse)
 	unsigned char resp[3];
 	int i;
 
-	for (i = 0; min_max_pnpid_table[i].pnp_ids; i++)
-		if (matches_pnp_id(psmouse, min_max_pnpid_table[i].pnp_ids)) {
-			priv->x_min = min_max_pnpid_table[i].x_min;
-			priv->x_max = min_max_pnpid_table[i].x_max;
-			priv->y_min = min_max_pnpid_table[i].y_min;
-			priv->y_max = min_max_pnpid_table[i].y_max;
-			return 0;
-		}
-
 	if (SYN_ID_MAJOR(priv->identity) < 4)
 		return 0;
 
@@ -366,6 +357,15 @@ static int synaptics_resolution(struct psmouse *psmouse)
 		}
 	}
 
+	for (i = 0; min_max_pnpid_table[i].pnp_ids; i++)
+		if (matches_pnp_id(psmouse, min_max_pnpid_table[i].pnp_ids)) {
+			priv->x_min = min_max_pnpid_table[i].x_min;
+			priv->x_max = min_max_pnpid_table[i].x_max;
+			priv->y_min = min_max_pnpid_table[i].y_min;
+			priv->y_max = min_max_pnpid_table[i].y_max;
+			return 0;
+		}
+
 	if (SYN_EXT_CAP_REQUESTS(priv->capabilities) >= 5 &&
 	    SYN_CAP_MAX_DIMENSIONS(priv->ext_cap_0c)) {
 		if (synaptics_send_cmd(psmouse, SYN_QUE_EXT_MAX_COORDS, resp)) {
-- 
1.9.0