Hi,
The sixaxis accelerometers/gyroscope from the joystick interface use a
"flat" value that causes an input range of length ~128 of 1024 to be
mapped to zero. This loses a lot of orientation information; for
example, it is possible to position the device diagonally such that
all three accelerometers are zero--meaning there is no force of
gravity.
I'm not sure if this warrants a bug report: Is it the intended
behavior, or a bad side-effect of the default settings?
For demonstration purposes, the following is a patch that attempts to
set the "flat" and "fuzz" values, but it is not very clean. These
values are reset to defaults AFTER the input_mapped function is
called, so it returns a negative value to bypass the rest of
hidinput_configure_usage(). (I am not very familiar with the input
subsystem, so maybe someone can suggest a more correct way to
accomplish this.) It should at least allow you to see the difference
in reported values.
Thanks for any suggestions on the issue.
David
--- a/drivers/hid/hid-sony.c 2011-09-02 19:34:52.833614001 -0400
+++ b/drivers/hid/hid-sony.c 2011-09-06 20:49:04.576358380 -0400
@@ -209,6 +209,36 @@ static void sony_remove(struct hid_devic
kfree(hid_get_drvdata(hdev));
}
+/*
+ * The default axis flat value for gamepads is [range length] >> 4 which, in
+ * the case of the 10-bit sixaxis accelerometers/gyroscope, loses too much
+ * information.
+ */
+static int sony_input_mapped(struct hid_device *hdev, struct hid_input *hi,
+ struct hid_field *field, struct hid_usage *usage,
+ unsigned long **bit, int *max)
+{
+ int a = field->logical_minimum;
+ int b = field->logical_maximum;
+
+ /* The 10-bit range identifies the accelerometers/gyroscope uniquely */
+ if (usage->hid == HID_GD_POINTER && a == 0x0000 && b == 0x03FF) {
+
+ /* This repeats hid-input.c code that had to be skipped */
+ set_bit(usage->type, hi->input->evbit);
+ while (usage->code <= *max && test_and_set_bit(usage->code, *bit))
+ usage->code = find_next_zero_bit(*bit, *max + 1, usage->code);
+
+ /* Specify a new fuzz and flat value */
+ input_set_abs_params(hi->input, usage->code, a, b, 4, 4);
+
+ /* Skip past the default post-mapping changes */
+ return -1;
+ }
+
+ return 0;
+}
+
static const struct hid_device_id sony_devices[] = {
{ HID_USB_DEVICE(USB_VENDOR_ID_SONY, USB_DEVICE_ID_SONY_PS3_CONTROLLER),
.driver_data = SIXAXIS_CONTROLLER_USB },
@@ -228,7 +258,8 @@ static struct hid_driver sony_driver = {
.probe = sony_probe,
.remove = sony_remove,
.report_fixup = sony_report_fixup,
- .raw_event = sony_raw_event
+ .raw_event = sony_raw_event,
+ .input_mapped = sony_input_mapped
};
static int __init sony_init(void)
--
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