Fwd: Improving drivers for Logitech Driving Force Pro and G25 wheels

["Richie Ward" <richies@gmail.com>]

I own a G25, Can you write out some of the knowledge you have acquired?

 On Fri, Mar 14, 2008 at 7:52 PM, chris guirl <thelusiv@gmail.com> wrote:
 > On Fri, Mar 14, 2008 at 5:42 AM, Jiri Kosina <jkosina@suse.cz> wrote:
 >  >  thanks for your mail, I have added Jean-Philippe to CC, who has sent me
 >  >  some time ago debugging information for this wheel, but I unfortunately
 >  >  didn't yet had time to look into that in more detail.
 >
 >  Which wheel, the DFP or the G25? Either way they are similar in many
 >  ways so better support for one would improve support for the other.
 >  I'm interested to see this information. There has been some discussion
 >  of the G25 on the forums at vdrift.net.
 >
 >  >  Regarding the HID code -- currently, all device-specific stuff for HID
 >  >  devices is implemented as quirks in hid code -- please see
 >  >  drivers/hid/hid-*quirks* and drivers/hid/usbhid/hid-quirks*.
This is not a
 >  >  solution that works well in long-term though, and Jiri Slaby (also added
 >  >  to CC) is currently rewriting the HID core code, so that it
will work as a
 >  >  proper bus, so individual drivers could work nicely with that. Once this
 >  >  is done, all the current quirks will be converted to HID-bus drivers.
 >
 >  I've looked through the quirks code and I have some suggestions for
 >  things that can be changed. First, the Vendor/product IDs of the
 >  wheels are not present. When the devices power up they assume VID:PID
 >  0x046d:0xc294 which there is a line for in
 >  drivers/hid/usbhid/hid-quirks.c:
 >
 >  #define USB_DEVICE_ID_LOGITECH_WHEEL    0xc294
 >
 >  This is used by the Logitech Formula Force or Driving Force wheel, and
 >  a legacy mode on the DFP & G25. To use the DFP or G25 in their native
 >  modes, they must be sent a command [0xf8, 0x01] or [0xf8, 0x10]
 >  respectively. Once these wheels receive this command, they simulate a
 >  detach and reattach as 0x046d:0xc298 and 0x046d:0xc299 respectively.
 >  These VID:PID combinations are not handled in the kernel at all. At
 >  the very least they need to be assigned the same quirks as the Driving
 >  Force.
 >
 >  When a Driving Force/Formula Force wheel is detected the device needs
 >  to be probed with the native mode commands to see if it will switch
 >  into DFP or G25 mode. If these modes work, then it is possible to send
 >  the wheels some other commands to enable full rotation of the wheel.
 >  By default only 200 degrees of rotation is available, but both the DFP
 >  and G25 can be switched to allow up to 900 degrees of rotation. I
 >  think there should be a user-land tool to change settings on the wheel
 >  such as this.
 >
 >  >  Depends on how massive your changes are going to be, you could either
 >  >  coordinate with Jiri so that no effort is wasted, or you can just send me
 >  >  a patch with simple quirks addition, and it will get converted
into hidbus
 >  >  driver later.
 >
 >  If there is a rewrite due then it may be best to work with Jiri so I
 >  can make my changes work with his, no sense in patching twice.
 >
 >  In addition to HID code, I think I'll need to make some changes to the
 >  joydev driver, as some other things need to be addressed (such as
 >  splitting the gas and brake axis up into separate, independent axes).
 >  Currently I am able to send raw commands to my DFP to make it change
 >  modes, but the /dev/input/jsX device disappears when I do this, so
 >  some other tweaks may be needed on the joystick end of things.
 >
 >  I'll be out of town this weekend so not working on anything yet, but
 >  please send any ideas along as I hope to get started next week.
 >  Thanks.
 >
 >  Chris
 >
 >
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 >



 --
 Thanks, Richie Ward



-- 
Thanks, Richie Ward