Re: [PATCH] Fix autocentering command in hid-lgff driver

Hello,

this patch fixes two issues with autocentering in lgff driver. Current
implementation incorrectly assumes that the saturation force is always
0x80 which is
inconsistent with behavior of the official driver. It also makes it
impossible to disable autocentering on some wheels - at least Logitech
Formula Force RX is
the case. Values of stiffness coefficient were also calculated
incorrectly. Formula used in this patch appears to generate the same
commands as the official
Logitech drivers. The patch also fixes two minor coding style issues.

Hi Michal,
Can you elaborate more on the difference between stiffness and saturation?
And how these might work in the Linux FF system which only accounts a
single parameter.

On my reverse engineering of the Wii Wheel (1) I noticed that the
AutoCentre consisted of 3 variables, but did realise the precise details.
Perhaps I can factor in a similar adjustment....

BTW - I also discovered some other modes of feedback beyond AutoCentre and
CF which might be applicable to other Logitech wheels. (2)

Simon

1.
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob;f=drivers/hid/hid-lg4ff.c;h=fa550c8e1d1bc639bd3e9c34a299903391bca44a;hb=3a2289a4a317e0290a8bc7af28c62c9830cb12e5#l72

2. http://wiibrew.org/wiki/Logitech_USB_steering_wheel