Re: Linux Force Feedback for Saitek Cyborg Evo Force

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

  Dec 29, 2009, at 4:46 AM, Johannes Ebke <johannes.ebke@physik.uni-muenchen.de 
 > wrote:

> Dmitry Torokhov wrote:
>> On Sun, Dec 20, 2009 at 11:44:19PM -0800, Dmitry Torokhov wrote:
>>> On Sun, Dec 20, 2009 at 12:36:23AM +0100, Johannes Ebke wrote:
>>>> Hi,
>>>>
>>>> It seems that the force feedback works well, I have ported the  
>>>> force
>>>> feedback for my favorite game to linux now, and it works well.
>>>>
>>>> What does not work is updating effects - there just nothing  
>>>> happens, and
>>>> the old event is played. I have circumvented this by
>>>> deleting/re-uploading the effect, but this should probably been  
>>>> made to
>>>> work. Does it work well with other hardware?
>>>>
>>>> Thirdly, I have re-discovered one kernel oops that occurs if the
>>>> joystick is unplugged if some process still has the event device  
>>>> open.
>>>> Steps to reproduce:
>>>> * plug joystick in
>>>> * fftest /dev/input/eventXX
>>>> * unplug joystick
>>>>
>>>> (kern.log extract attached)
>>>>
>>>> Sometimes this just gives an oops, sometimes it escalates into a  
>>>> kernel
>>>> panic.
>>>>
>>> Hmm, it looks like iforce unbinding is completely busted:
>>>
>>> static void iforce_usb_disconnect(struct usb_interface *intf)
>>> {
>>>        struct iforce *iforce = usb_get_intfdata(intf);
>>>        int open = 0; /* FIXME! iforce->dev.handle->open; */
>>> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>>>
>>>        usb_set_intfdata(intf, NULL);
>>>        if (iforce) {
>>>                iforce->usbdev = NULL;
>>>                input_unregister_device(iforce->dev);
>>>
>>>                if (!open) {
>>>                        iforce_delete_device(iforce);
>>>                        kfree(iforce);
>>>                }
>>>        }
>>> }
>>>
>>>
>>> Any chance you could fix that FIXME ;) ?
>>>
>>
>> Actually, does the below fixes it for you?
>>
>
> This fixes the kernel oops - thanks! However it also disables FF,  
> unless
> I remove "usb_kill_urb(iforce->out);" from iforce_close.
> From some debug statements I found that iforce_close is called twice  
> if
> you just plug in the joystick, so the effect is immediate.

I still believe that usb_kill_urb is needed however we need to wait  
for packet disabling FF to complete.

>
> However, when I unplug the joystick while having it open, I get some
> input input22: usb_submit_urb failed -19
> messages in dmesg (after iforce_disconnect but before iforce_close)
> This is probably what should happen, however.
>

This is indeed expected with surprise removals.

-- 
Dmitry