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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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