[ adding some more CCs ]
I haven't been really succesfull extracting the nature of the problem from
the mail below. Could you please sum it up for the people who haven't seen
the thread from the beginning?
Thanks.
--
Jiri Kosina
SUSE Labs, Novell Inc.
On Tue, 5 Jan 2010, wylda@xxxxxxxx wrote:
> Hi Peter,
>
> i'm definitely interested, but i'm not a developer. So i try to resend
> this mail to guys who helped last time in hope, they will be interested
> again and maybe they can provide you some info. I'm able to give just
> feedback based on patches and tests.
>
> Hi Jiri & Christophe,
> if you remember 15.6. ~ 23.6.2009 (subject: "Force feedback for Logitech
> WingMan Formula Force GP") you help me with force feedback on my logitech
> wheel and thus kernel support this wheel. Peter found some anomalies
> in behaviour/code and would like to consult that stuff.
>
> Sorry if this mail bothers you and you have other things to do...
>
> Regards,
> Pavel V.
>
> PS: I would like to stay in touch, so can you leave me on CC?
>
> ----- PŮVODNÍ ZPRÁVA -----
> Od: "Peter" <peter@xxxxxxxxxxx>
> Komu: wylda@xxxxxxxx
> Předmět: Re: Question: Formula Force GP (Force) Feedback
> Datum: 5.1.2010 - 17:20:15
>
> > Hi,
> >
> > you might be interested that im getting closer to finding
> > the source of
> > the problem.
> >
> > from drivers/hid/hid-lgff.c:
> > > static int hid_lgff_play(struct input_dev *dev, void
> > > *data, struct ff_effect *effect)
> > > > {
> > > struct hid_device *hid = input_get_drvdata(dev);
> > > > > > struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list;
> > > > > > > struct hid_report *report = list_entry(report_list->next,
> > > > > > struct hid_report, list);
> > > > int x, y;
> > > unsigned int left, right;
> > >
> > > #define CLAMP(x) if (x < 0) x = 0; if (x > 0xff)
> > > x = 0xff
> > > >
> > > switch (effect->type)
> > > {
> > > case FF_CONSTANT:
> > > x = effect->u.ramp.start_level
> > > + 0x7f; /* 0x7f is center
> > > */
> > > > y = effect->u.ramp.end_level
> > > > > > + 0x7f; /**/
> > >
> > i modified the last two lines and got (after some tests)
> > an idea how to interpret the 2
> > values and ho they correspond... funny thing is, that
> > the wheel
> > responds to both axes.
> >
> > 255 o < << <<< <<<<
> > 191 > o < << <<<
> > 127 >> > o < <<
> > 63 >>> >> > o <
> > 0 >>>> >>> >> > o
> > 0 63 127 191 255
> >
> > The problem (as far as i understand it now) seems to
> > be, that
> > effect->u.ramp.start_level should have a value between
> > -128 and 127,
> > but only goes from 0 to 127. How and why, i have no
> > idea so far, since
> > it doesnt seem to be an overflow, but im not so sure
> > right now. The
> > result however depends on the application and goes
> > from when the wheel
> > goes over center position, it jumps from soft left
> > to full left force
> > or just correct forcestrength, but only into the same
> > direction on both
> > sides.
> >
> > I dont know if youre the right person for this, since
> > the code in
> > hid-lgff.c doesnt seem to be written from you and your
> > commit doesnt
> > touch it. If you've got no idea, just drop me a note
> > :)
> >
> > Bye, Peter
>
>
--
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
