On Mon, Jan 11, 2016 at 12:25 AM, Edwin Velds <e.velds@xxxxxxxxx> wrote: > This patch implements force feedback support for the Logitech > G920 Driving Force Racing Wheel. It is a generic implementation > of feature 0x8123 of the Logitech HID++ protocol and should be > usable for any future devices that implement this feature. > > This patch should be applied after the basic G920 support patch > by Simon Wood: > http://www.spinics.net/lists/linux-input/msg42174.html > > The driving supports everything that is supported by the G920 > firmware: > FF_CONSTANT > FF_PERIODIC > FF_SINE > FF_SQUARE > FF_SAW_UP > FF_SAW_DOWN > FF_TRIANGLE > FF_SPRING > FF_DAMPER > FF_AUTOCENTER > FF_GAIN > and for version 2 firmware also: > FF_FRICTION > FF_INERTIA > FF_RAMP > > Both envelopes and replay values are supported as well, but some > problems may occur when using firmware release 1. There is also a > small residual clockwise damper in the wheel when using the first > firmware release. All problems are fixed in the soon te be released > firmware version 2. > > The default spring is disabled by permanently placing a spring > force in the wheel. This spring is also used as the autocenter > spring. > > Signed-off-by: Edwin Velds <e.velds@xxxxxxxxx> Tested-by: Elias Vanderstuyft <elias.vds@xxxxxxxxx> Tested with both firmware version 1 and firmware version 2. @Dmitry: As side note, Edwin intentionally did *not* put a clamp(0, 0x7FFF, x) in the driver, with x being envelope.attack_level or envelope.fade_level, since this parameter checking is (/ should be) the task of "ff_core.c". The device will behave odd when playing an effect that violates this rule, although most user-space programs don't let them exceed 0x7FFF. So this is a TODO for "ff-core.c", but not a blocker for this patch, since the odd behavior will only be triggered during playback of such violating effect, and vanishes when the effect stops. Other note: For anyone who is interested on which spec this patch is based, take a look at the excellently written "Logitech Force Feedback Protocol" document: https://opensource.logitech.com/opensource/index.php/Technical_Information Thanks, Elias -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
