[PATCH evdev] Only force REL_X/Y if no ABS_X/Y exists

[Chase Douglas]

On 01/25/2012 05:37 PM, Peter Hutterer wrote:
> On Wed, Jan 25, 2012 at 07:48:27PM +0100, Chase Douglas wrote:
>> On 01/25/2012 07:26 AM, Peter Hutterer wrote:
>>> 5c5b2c8db851df7921cedd888222a6630a007fd8 added forced x/y axes if a device
>>> has any axes of the same mode. This was too broad a brush, some devices have
>>> a relative wheel but absolute x/y axes and would now get misdetected as
>>> purely relative device.
>>>
>>> Only force relative axes if a device no rel x/y _and_ no abs x/y.
>>>
>>> Reproducible: virtual machine with QEMU USB Tablet will stop working
>>>
>>> Signed-off-by: Peter Hutterer <peter.hutterer at who-t.net>
>>> ---
>>>  src/evdev.c |   18 ++++++++++--------
>>>  1 files changed, 10 insertions(+), 8 deletions(-)
>>>
>>> diff --git a/src/evdev.c b/src/evdev.c
>>> index 32fe38b..a6f9a59 100644
>>> --- a/src/evdev.c
>>> +++ b/src/evdev.c
>>> @@ -2125,6 +2125,13 @@ EvdevProbe(InputInfoPtr pInfo)
>>>          }
>>>      }
>>>  
>>> +    for (i = 0; i < ABS_MAX; i++) {
>>> +        if (EvdevBitIsSet(pEvdev->abs_bitmask, i)) {
>>> +            has_abs_axes = TRUE;
>>> +            break;
>>> +        }
>>> +    }
>>> +
>>>      if (has_rel_axes) {
>>>          if (EvdevBitIsSet(pEvdev->rel_bitmask, REL_WHEEL) ||
>>>              EvdevBitIsSet(pEvdev->rel_bitmask, REL_HWHEEL) ||
>>> @@ -2146,7 +2153,9 @@ EvdevProbe(InputInfoPtr pInfo)
>>>              if (EvdevBitIsSet(pEvdev->rel_bitmask, REL_X) &&
>>>                  EvdevBitIsSet(pEvdev->rel_bitmask, REL_Y)) {
>>>                  xf86IDrvMsg(pInfo, X_PROBED, "Found x and y relative axes\n");
>>> -            } else
>>> +            } else if (!has_abs_axes ||
>>> +                       !EvdevBitIsSet(pEvdev->abs_bitmask, ABS_X) ||
>>> +                       !EvdevBitIsSet(pEvdev->abs_bitmask, ABS_Y))
>>
>> !has_abs_axes implies !EvdevBitIsSet(pEvdev->abs_bitmask, ABS_X) and
>> !EvdevBitIsSet(pEvdev->abs_bitmask, ABS_Y). If I'm parsing the logic
>> right, we don't need the check for !has_abs_axes. There is no case in
>> which !has_abs_axes can be true but the ABS_X and ABS_Y are not present.
> 
> yeah, you're right, it's a bit superfluous and was mainly intended to skip
> the bit-checks if we don't have axes at all. but given that it's just a bit
> check, this isn't a performance issue here, so I'll just remove the
> !has_abs_axes part.

Alternatively, you could add a variable has_abs_x_y. Maybe it would make
the code more readable? It's a bit bike-sheddy though.

Either way, with the removal of the check for has_abs_axes:

Reviewed-by: Chase Douglas <chase.douglas at canonical.com>