Re: Bug: HID-Sony: DS4 touch-pad corrupts Axis0

[Frank Praznik <frank.praznik@gmail.com>]

On 4/21/2014 13:30, Frank Praznik wrote:
> On 4/21/2014 12:49, simon@mungewell.org wrote:
>> Hi,
>> I've noticed a glitch with the Dualshock4 on 3.15rc1 (plus LEDs 
>> patch, if
>> that makes a difference).
>>
>> Sometimes everything works as expected, the thumbsticks work OK and the
>> touch-pad changes axis 15 & 16 (as reported by jstest). Other times axis
>> 15 and 16 do not report changes, instead axis 0 is corrupted/changed 
>> when
>> the touch-pad is 'swiped'.
>>
>> Evtest appears to report correctly all the time.
>>
>> It seems that the controller works first time it is plugged in (after
>> boot), but then fails subsequent times. I think that the first time I
>> don't get the pop-up message about battery being charged, which 
>> occurs on
>> other times.
>>
>> I have not found a trigger yet, but was wondering whether others are
>> seeing this. I am using a USB connected DS4 (no BT on this machine). 
>> OS is
>> Xubuntu 13.10 with patched kernel,
>> Simon.
>>
>> -- 
>> simon@slipstream:~$ jstest /dev/input/js0
>> Driver version is 2.1.0.
>> Joystick (Sony Computer Entertainment Wireless Controller) has 14 
>> axes (X,
>> Y, Z,
>> and 14 buttons (BtnX, BtnY, BtnZ, BtnTL, BtnTR, BtnTL2, BtnTR2, 
>> BtnSelect,
>> BtnSt
>> Testing ... (interrupt to exit)
>> -- 
>> Apr 21 10:21:01 slipstream kernel: [  818.052095] usb 5-1: USB 
>> disconnect,
>> devic
>> Apr 21 10:21:33 slipstream kernel: [  849.684027] usb 5-1: new 
>> full-speed
>> USB de
>> Apr 21 10:21:33 slipstream kernel: [  849.855036] usb 5-1: New USB 
>> device
>> found,
>> Apr 21 10:21:33 slipstream kernel: [  849.855041] usb 5-1: New USB 
>> device
>> string
>> Apr 21 10:21:33 slipstream kernel: [  849.855045] usb 5-1: Product:
>> Wireless Con
>> Apr 21 10:21:33 slipstream kernel: [  849.855049] usb 5-1: Manufacturer:
>> Sony Co
>> Apr 21 10:21:33 slipstream kernel: [  849.861096] sony
>> 0003:054C:05C4.0005: Usin
>> Apr 21 10:21:33 slipstream kernel: [  849.906141] input: Sony Computer
>> Entertain
>> Apr 21 10:21:33 slipstream kernel: [  849.906344] sony
>> 0003:054C:05C4.0005: inpu
>> -- 
>>
>>
>
> I've seen this before and it's a bug in jstest and jstest-gtk, not the 
> driver or event system.  These programs do their own internal axis 
> mapping and don't properly handle axes above ABS_MISC which is where 
> the touch axes are.  jstest-gtk just default maps these to 0 and the 
> old jstest just doesn't look like it does any bounds checking at all.

Sorry, it seems that I spoke too soon (jstest-gtk has an internal bug 
that causes this exact problem, but the old jstest doesn't).

The joydev device *is* missing the mappings for the touchpad axes for 
some reason (JSIOCGAXES returns 14 instead of 17 like it should).  I'm 
not sure why though.  In the Sony driver the touchpad axis bits are set 
in the probe function and work correctly via the evdev interface and 
looking in the joydev module it should properly handle and map all axes 
up to ABS_MAX so the problem probably lies somewhere else.  If I had to 
guess, it seems like the joydev device is being created after the HID 
descriptor is parsed, but before the device probe function is called.

Can anyone more familiar with the general input system comment on why 
this might be happening?