Input: elantech - fix touchpad initialization on Gigabyte U2442

commit 36189cc3cd57ab0f1cd75241f93fe01de928ac06 upstream.

The hw_version 3 Elantech touchpad on the Gigabyte U2442 does not accept
0x0b as initialization value for r10, this stand-alone version of the
driver: http://planet76.com/drivers/elantech/psmouse-elantech-v6.tar.bz2

Uses 0x03 which does work, so this means not setting bit 3 of r10 which
sets: "Enable Real H/W Resolution In Absolute mode"

Which will result in half the x and y resolution we get with that bit set,
so simply not setting it everywhere is not a solution. We've been unable to
find a way to identify touchpads where setting the bit will fail, so this
patch uses a dmi based blacklist for this.

https://bugzilla.kernel.org/show_bug.cgi?id=61151

Reported-by: Philipp Wolfer <ph.wolfer@gmail.com>
Tested-by: Philipp Wolfer <ph.wolfer@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/Documentation/input/elantech.txt b/Documentation/input/elantech.txt
index 5602eb7..e1ae127 100644 (file)
--- a/Documentation/input/elantech.txt
+++ b/Documentation/input/elantech.txt
@@ -504,9 +504,12 @@ byte 5:
 * reg_10
 
    bit   7   6   5   4   3   2   1   0
-         0   0   0   0   0   0   0   A
+         0   0   0   0   R   F   T   A
 
          A: 1 = enable absolute tracking
+         T: 1 = enable two finger mode auto correct
+         F: 1 = disable ABS Position Filter
+         R: 1 = enable real hardware resolution
 
 6.2 Native absolute mode 6 byte packet format
     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

diff --git a/drivers/input/mouse/elantech.c b/drivers/input/mouse/elantech.c
index e2a9867..342a059 100644 (file)
--- a/drivers/input/mouse/elantech.c
+++ b/drivers/input/mouse/elantech.c
@@ -11,6 +11,7 @@
  */
 
 #include <linux/delay.h>
+#include <linux/dmi.h>
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/input.h>
@@ -783,7 +784,11 @@ static int elantech_set_absolute_mode(struct psmouse *psmouse)
                break;
 
        case 3:
-               etd->reg_10 = 0x0b;
+               if (etd->set_hw_resolution)
+                       etd->reg_10 = 0x0b;
+               else
+                       etd->reg_10 = 0x03;
+
                if (elantech_write_reg(psmouse, 0x10, etd->reg_10))
                        rc = -1;
 
@@ -1205,6 +1210,22 @@ static int elantech_reconnect(struct psmouse *psmouse)
        return 0;
 }
 
+/*
+ * Some hw_version 3 models go into error state when we try to set bit 3 of r10
+ */
+static const struct dmi_system_id no_hw_res_dmi_table[] = {
+#if defined(CONFIG_DMI) && defined(CONFIG_X86)
+       {
+               /* Gigabyte U2442 */
+               .matches = {
+                       DMI_MATCH(DMI_SYS_VENDOR, "GIGABYTE"),
+                       DMI_MATCH(DMI_PRODUCT_NAME, "U2442"),
+               },
+       },
+#endif
+       { }
+};
+
 /*
  * determine hardware version and set some properties according to it.
  */
@@ -1254,6 +1275,9 @@ static int elantech_set_properties(struct elantech_data *etd)
                        etd->reports_pressure = true;
        }
 
+       /* Enable real hardware resolution on hw_version 3 ? */
+       etd->set_hw_resolution = !dmi_check_system(no_hw_res_dmi_table);
+
        return 0;
 }
 

diff --git a/drivers/input/mouse/elantech.h b/drivers/input/mouse/elantech.h
index 9e5f1aa..3569bed 100644 (file)
--- a/drivers/input/mouse/elantech.h
+++ b/drivers/input/mouse/elantech.h
@@ -128,6 +128,7 @@ struct elantech_data {
        bool paritycheck;
        bool jumpy_cursor;
        bool reports_pressure;
+       bool set_hw_resolution;
        unsigned char hw_version;
        unsigned int fw_version;
        unsigned int single_finger_reports;