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Subject[PATCH v2] hid: Fix Logitech Driving Force Pro wheel
Date
Changes from initial patch:
- shorten comment (removed original descriptor)
- optimized new descriptor (simpler and shorter)

This is a patch for hid-lg.c which fixes the Logitech Driving Force Pro driver.
It was generated against vanilla 2.6.39.
It contains two parts:
- Add the quirk "NOGET" to make the wheel work at all in native mode.
- Replace the somehow broken report descriptor with a custom one to have
separate throttle and brake axes.

As there are significant differences in the descriptor (original descriptor
"hides" the separate axes in a 24 bit FF00 usagepage, new descripter replaces
that with two individual 8 bit desktop.y and desktop.rz usages) I provided a
complete replacement descriptor instead trying to patch the original one.
Patching the descriptor seems not feasible as the new one is much larger.

Note: To actually test this you have to use the tool "ltwheelconf" to put the
DFP into it's native mode - See below for more info.


Background:
Most Logitech wheels are initially reporting themselves with a "fallback"
deviceID (USB_DEVICE_ID_LOGITECH_WHEEL - 0xc294), in order to make sure they
are working even without having the proper driver installed.
If the Logitech driver is installed it sends a special command to the wheel
which sets the wheel to "native mode", enabling enhance features like:
- Clutch pedal
- extended wheel rotation range (up to 900 degrees)
- H-gate shifter
- separate axis for throttle / brake
- all buttons
When the wheel is set to native mode it basically disconnects and reconnects
with a different deviceID (USB_DEVICE_ID_LOGITECH_DFP_WHEEL - 0xc298 in this
case).
I am working on a userspace tool [1] which does the switching from fallback to
native mode. During development I found out that the Driving Force Pro wheel
is not supported in native mode - quierk NOGET is missing and the throttle and
brake axes are reported in a combined way only.


Signed-off-by: Michael Bauer <michael@m-bauer.org>

[1] https://github.com/TripleSpeeder/LTWheelConf

---
--- 2.6.39_vanilla/drivers/hid/hid-lg.c 2011-05-19 06:06:34.000000000 +0200
+++ 2.6.39/drivers/hid/hid-lg.c 2011-05-30 21:49:51.535184784 +0200
@@ -41,6 +41,66 @@
#define LG_FF3 0x1000
#define LG_FF4 0x2000

+/* Size of the original descriptor of the Driving Force Pro wheel */
+#define DFP_RDESC_ORIG_SIZE 97
+
+/* Fixed report descriptor for Logitech Driving Force Pro wheel controller
+ *
+ * The original descriptor hides the separate throttle and brake axes in
+ * a custom vendor usage page, providing only a combined value as
+ * GenericDesktop.Y.
+ * This descriptor removes the combined Y axis and instead reports
+ * separate throttle (Y) and brake (RZ).
+ */
+static __u8 dfp_rdesc_fixed[] = {
+0x05, 0x01, /* Usage Page (Desktop), */
+0x09, 0x04, /* Usage (Joystik), */
+0xA1, 0x01, /* Collection (Application), */
+0xA1, 0x02, /* Collection (Logical), */
+0x95, 0x01, /* Report Count (1), */
+0x75, 0x0E, /* Report Size (14), */
+0x14, /* Logical Minimum (0), */
+0x26, 0xFF, 0x3F, /* Logical Maximum (16383), */
+0x34, /* Physical Minimum (0), */
+0x46, 0xFF, 0x3F, /* Physical Maximum (16383), */
+0x09, 0x30, /* Usage (X), */
+0x81, 0x02, /* Input (Variable), */
+0x95, 0x0E, /* Report Count (14), */
+0x75, 0x01, /* Report Size (1), */
+0x25, 0x01, /* Logical Maximum (1), */
+0x45, 0x01, /* Physical Maximum (1), */
+0x05, 0x09, /* Usage Page (Button), */
+0x19, 0x01, /* Usage Minimum (01h), */
+0x29, 0x0E, /* Usage Maximum (0Eh), */
+0x81, 0x02, /* Input (Variable), */
+0x05, 0x01, /* Usage Page (Desktop), */
+0x95, 0x01, /* Report Count (1), */
+0x75, 0x04, /* Report Size (4), */
+0x25, 0x07, /* Logical Maximum (7), */
+0x46, 0x3B, 0x01, /* Physical Maximum (315), */
+0x65, 0x14, /* Unit (Degrees), */
+0x09, 0x39, /* Usage (Hat Switch), */
+0x81, 0x42, /* Input (Variable, Nullstate), */
+0x65, 0x00, /* Unit, */
+0x26, 0xFF, 0x00, /* Logical Maximum (255), */
+0x46, 0xFF, 0x00, /* Physical Maximum (255), */
+0x75, 0x08, /* Report Size (8), */
+0x81, 0x01, /* Input (Constant), */
+0x09, 0x31, /* Usage (Y), */
+0x81, 0x02, /* Input (Variable), */
+0x09, 0x35, /* Usage (Rz), */
+0x81, 0x02, /* Input (Variable), */
+0x81, 0x01, /* Input (Constant), */
+0xC0, /* End Collection, */
+0xA1, 0x02, /* Collection (Logical), */
+0x09, 0x02, /* Usage (02h), */
+0x95, 0x07, /* Report Count (7), */
+0x91, 0x02, /* Output (Variable), */
+0xC0, /* End Collection, */
+0xC0 /* End Collection */
+};
+
+
/*
* Certain Logitech keyboards send in report #3 keys which are far
* above the logical maximum described in descriptor. This extends
@@ -74,6 +134,18 @@ static __u8 *lg_report_fixup(struct hid_
rdesc[47] = 0x95;
rdesc[48] = 0x0B;
}
+
+ switch (hdev->product) {
+ case USB_DEVICE_ID_LOGITECH_DFP_WHEEL:
+ if (*rsize == DFP_RDESC_ORIG_SIZE) {
+ hid_info(hdev,
+ "fixing up Logitech Driving Force Pro report descriptor\n");
+ rdesc = dfp_rdesc_fixed;
+ *rsize = sizeof(dfp_rdesc_fixed);
+ }
+ break;
+ }
+
return rdesc;
}

@@ -378,7 +450,7 @@ static const struct hid_device_id lg_dev
{ HID_USB_DEVICE(USB_VENDOR_ID_LOGITECH,
USB_DEVICE_ID_LOGITECH_G25_WHEEL),
.driver_data = LG_FF },
{ HID_USB_DEVICE(USB_VENDOR_ID_LOGITECH,
USB_DEVICE_ID_LOGITECH_DFP_WHEEL),
- .driver_data = LG_FF },
+ .driver_data = LG_NOGET | LG_FF },
{ HID_USB_DEVICE(USB_VENDOR_ID_LOGITECH,
USB_DEVICE_ID_LOGITECH_WII_WHEEL),
.driver_data = LG_FF4 },
{ HID_USB_DEVICE(USB_VENDOR_ID_LOGITECH,
USB_DEVICE_ID_LOGITECH_WINGMAN_FFG ),


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