Re: [PATCH] joydev.c automatic re-calibration

["Renato Golin" <rengolin@gmail.com>]

This small patch adds the automatic recalibration feature without
spoiling previously calibrated devices. It's a fix for those joysticks
that report faulty range, specially Saitek Cyborg Evo Force.

File: drivers/input/joydev.c
Fix:
 - extracted code from joydev_connect to method
joydev_calculate_correction to be able to call it from both
joydev_event upon recalibration and joydev_connect during first
connection.
 - on joydev_connect check ranges and zero calibration if found out of range
 - on joydev_event, every time found out of range, update min/max and
recalculate the correction

PS: adding Signed-off-by line (is that it?)

Signed-off-by: Renato Golin <rengolin@gmail.com>
$ diff -u joydev.c.original joydev.c
--- joydev.c.original   2007-05-22 22:23:43.000000000 +0100
+++ joydev.c    2007-05-23 01:24:04.000000000 +0100
@@ -53,6 +53,8 @@
       __u8 absmap[ABS_MAX + 1];
       __u8 abspam[ABS_MAX + 1];
       __s16 abs[ABS_MAX + 1];
+       __s16 absmin[ABS_MAX + 1];
+       __s16 absmax[ABS_MAX + 1];
 };

 struct joydev_list {
@@ -67,6 +69,19 @@

 static struct joydev *joydev_table[JOYDEV_MINORS];

+static void joydev_calculate_correction(int min, int max, int axis,
struct joydev *joydev)
+{
+       int t, j = joydev->abspam[axis];
+       int flat = joydev->handle.dev->absflat[j];
+
+       joydev->corr[axis].coef[0] = (max + min) / 2 - flat;
+       joydev->corr[axis].coef[1] = (max + min) / 2 + flat;
+       if (!(t = ((max - min) / 2 - 2 * flat)))
+               return;
+       joydev->corr[axis].coef[2] = (1 << 29) / t;
+       joydev->corr[axis].coef[3] = (1 << 29) / t;
+}
+
 static int joydev_correct(int value, struct js_corr *corr)
 {
       switch (corr->type) {
@@ -103,6 +118,14 @@
               case EV_ABS:
                       event.type = JS_EVENT_AXIS;
                       event.number = joydev->absmap[code];
+                       /* recalibration if needed */
+                       if (value < joydev->absmin[code]) {
+                               joydev->absmin[code] = value;
+                               joydev_calculate_correction(value,
joydev->absmax[code], code, joydev);
+                       } else if (value > joydev->absmax[code]) {
+                               joydev->absmax[code] = value;
+
joydev_calculate_correction(joydev->absmin[code], value, code,
joydev);
+                       }
                       event.value = joydev_correct(value,
joydev->corr + event.number);
                       if (event.value == joydev->abs[event.number])
                               return;
@@ -470,7 +493,7 @@
 {
       struct joydev *joydev;
       struct class_device *cdev;
-       int i, j, t, minor;
+       int i, j, minor;

       for (minor = 0; minor < JOYDEV_MINORS && joydev_table[minor]; minor++);
       if (minor == JOYDEV_MINORS) {
@@ -515,19 +538,21 @@

       for (i = 0; i < joydev->nabs; i++) {
               j = joydev->abspam[i];
-               if (dev->absmax[j] == dev->absmin[j]) {
+               joydev->absmin[i] = dev->absmin[j];
+               joydev->absmax[i] = dev->absmax[j];
+               if (joydev->absmax[i] == joydev->absmin[i]) {
                       joydev->corr[i].type = JS_CORR_NONE;
                       joydev->abs[i] = dev->abs[j];
                       continue;
               }
               joydev->corr[i].type = JS_CORR_BROKEN;
               joydev->corr[i].prec = dev->absfuzz[j];
-               joydev->corr[i].coef[0] = (dev->absmax[j] +
dev->absmin[j]) / 2 - dev->absflat[j];
-               joydev->corr[i].coef[1] = (dev->absmax[j] +
dev->absmin[j]) / 2 + dev->absflat[j];
-               if (!(t = ((dev->absmax[j] - dev->absmin[j]) / 2 - 2 *
dev->absflat[j])))
-                       continue;
-               joydev->corr[i].coef[2] = (1 << 29) / t;
-               joydev->corr[i].coef[3] = (1 << 29) / t;
+
+               if (dev->abs[j] > joydev->absmax[i] || dev->abs[j] <
joydev->absmin[i]) {
+                       printk("Joydev: Bad axis range, recalibrating
automatically\n");
+                       joydev_calculate_correction(0, 0, i, joydev);
+               } else
+                       joydev_calculate_correction(joydev->absmin[i],
joydev->absmax[i], i, joydev);

               joydev->abs[i] = joydev_correct(dev->abs[j], joydev->corr + i);
       }