Re: Missing axis on Gembird JPD-DUALFORCE2 since Linux 3.18

[Orivej Desh <orivej@gmx.fr>]

* Benjamin Tissoires
> Thanks for the logs.
> 
> So, yes, it appears that your joypad as a weird report descriptor.
> It declares 2 Z axis, no Ry and one Rz.
>
> The first Z axis seems somewhat correlated to X, but does not seem to
> add any actual value but noise.

That's right.

> If I understand correctly your problem, I can submit a patch which
> will mute the Z axis, and provide proper Rx,Ry so you won't have to
> deal with that in userspace.
> Will this be OK with you?

I would appreciate it if you do this, and learn to do it myself!  Yet I
think that Z axis is better removed than muted; it serves no purpose and
would only confuse other users of this device (if any) when tools
present them with 7 axes to configure.

> On Mon, Aug 10, 2015 at 5:36 PM, Orivej Desh <orivej@gmx.fr> wrote:
> > * Benjamin Tissoires
> >> Thanks for the bisect. Could you please run a hid-recorder from
> >> http://bentiss.github.io/hid-replay-docs/ and record a few events from
> >> your joypad? Depending on the output, we will be able to tell you
> >> where this should be fixed (but I strongly suspect that the kernel
> >> should be fixed).
> >
> > See attached idle.hid, with what appears to be noise on the Z axis when
> > the joypad is idle, and XYRxRy.hid with my approximation to the sequence
> > of physical X Y Rx Ry zero-negative-positive-zero swings.
> 
> >> On Mon, Aug 10, 2015 at 4:26 AM, Orivej Desh <orivej@gmx.fr> wrote:
> >> > I have one of those gamepads, and since Linux 3.18 the kernel hides one
> >> > of its axes.
> >> >
> >> > In Linux 3.17 jstest reports it as
> >> >
> >> >      Joystick (PC Game Controller       ) has 7 axes (X, Y, Z, Rx, Rz, Hat0X, Hat0Y)
> >> >
> >> > and in Linux 3.18 as
> >> >
> >> >      Joystick (PC Game Controller       ) has 6 axes (X, Y, Z, Rz, Hat0X, Hat0Y)
> >> >
> >> > It has 6 physical axes (X, Y, Rx, Ry, Hat0X, Hat0Y), but Ry is reported
> >> > as Rz, and Z emits noise (which had to be silenced with jscal).
> >> >
> >> > I bisected disappearing axis to the following commit [1], but if I
> >> > understand correctly, it is the device that is wrong by misreporting
> >> > some property of Rx.
> >> >
> >> > I can remap Rz to Ry in userspace with ioctl(fd, JSIOCSAXMAP, ...),
> >> > though I never had to.  Can I likewise restore Rx in userspace (and also
> >> > delete Z)?  If not, or if this device justifies a quirk, how should it
> >> > be added?
> >> >
> >> > usb-devices report: [2].
> >> >
> >> > [1]
> >> > commit 79346d620e9de87912de73337f6df8b7f9a46888
> >> > Author: Benjamin Tissoires <benjamin.tissoires@redhat.com>
> >> > Date:   Mon Aug 25 13:07:10 2014 -0400
> >> >
> >> >     HID: input: force generic axis to be mapped to their user space axis
> >> >
> >> >     Atmel 840B digitizer presents a stylus interface which reports twice
> >> >     the X coordinate and then twice the Y coordinate. In its current
> >> >     implementation, hid-input assign the first X to X, then the second to Y,
> >> >     then the first Y to Z, then the second one to RX.
> >> >
> >> >     This is wrong, and X should always be mapped to X, no matter what.
> >> >     A solution consists in forcing X, Y, Z, RX, RY, RZ to be mapped to their
> >> >     correct user space counter part.
> >> >
> >> >     Reported-by: Éric Brunet <Eric.Brunet@lps.ens.fr>
> >> >     Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
> >> >     Signed-off-by: Jiri Kosina <jkosina@suse.cz>
> >> >
> >> > diff --git a/drivers/hid/hid-input.c b/drivers/hid/hid-input.c
> >> > index 2619f7f..2df7fdd 100644
> >> > --- a/drivers/hid/hid-input.c
> >> > +++ b/drivers/hid/hid-input.c
> >> > @@ -599,6 +599,12 @@ static void hidinput_configure_usage(struct hid_input *hidinput, struct hid_fiel
> >> >                 /* These usage IDs map directly to the usage codes. */
> >> >                 case HID_GD_X: case HID_GD_Y: case HID_GD_Z:
> >> >                 case HID_GD_RX: case HID_GD_RY: case HID_GD_RZ:
> >> > +                       if (field->flags & HID_MAIN_ITEM_RELATIVE)
> >> > +                               map_rel(usage->hid & 0xf);
> >> > +                       else
> >> > +                               map_abs_clear(usage->hid & 0xf);
> >> > +                       break;
> >> > +
> >> >                 case HID_GD_SLIDER: case HID_GD_DIAL: case HID_GD_WHEEL:
> >> >                         if (field->flags & HID_MAIN_ITEM_RELATIVE)
> >> >                                 map_rel(usage->hid & 0xf);
> >> >
> >> > [2]
> >> > T:  Bus=09 Lev=01 Prnt=01 Port=01 Cnt=01 Dev#=  2 Spd=1.5 MxCh= 0
> >> > D:  Ver= 1.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 8 #Cfgs=  1
> >> > P:  Vendor=11ff ProdID=3331 Rev=01.07
> >> > S:  Product=PC Game Controller
> >> > C:  #Ifs= 1 Cfg#= 1 Atr=80 MxPwr=500mA
> >> > I:  If#= 0 Alt= 0 #EPs= 2 Cls=03(HID  ) Sub=00 Prot=00 Driver=usbhid
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