Re: [PATCH 03/12] Input: synaptics - fix minimum reported ABS_TOOL_WIDTH

Daniel Kurtz
2011-06-29T16:48:47Z

Hi Chris,

Thanks for taking a look!

On Wed, Jun 29, 2011 at 9:28 PM, Chris Bagwell <chris@cnpbagwell.com> wrote:
> On Wed, Jun 29, 2011 at 12:07 AM,  <djkurtz@chromium.org> wrote:
>> From: Daniel Kurtz <djkurtz@chromium.org>
>>
>> Synaptics touchpads report a 'w' value in each data report.
>> For touchpads that support palm detection, when there is a single finger
>> on the pad, the 'w' value reports its width in the range 4 to 15.
>> Thus, the minimum valid width is 4.
>
> FYI: I had debated on this as well.  When driver was first modified to
> report min/max width, the min width of zero was chosen because when
> not touching the pad a value of zero is forced by driver to user.  So
> the range is 0, 4-15.

Yup, good catch. I now see that this is true for the legacy single-touch case.
For consistency with the existing implementation, I'm ok to drop this patch.

I think we can still keep the range 4-15 for the ABS_MT_TOUCH_MAJOR
axis, though, right?
A pure-mt userspace app can get the correct width range, and deduce 0
fingers from the fact that all MT-B slots have tracking_id == -1.

-Dan

>>
>> Note: Other values of 'w' are used to report special conditions:
>>  w=0: 2 fingers are on the pad
>>  w=1: 3 or more fingers are on the pad
>>  w=2: the packet contains "Advanced Gesture Mode" data.
>>
>> Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
>> ---
>>  drivers/input/mouse/synaptics.c |    2 +-
>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>
>> diff --git a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptics.c
>> index f6d0c04..a4b7801 100644
>> --- a/drivers/input/mouse/synaptics.c
>> +++ b/drivers/input/mouse/synaptics.c
>> @@ -706,7 +706,7 @@ static void set_input_params(struct input_dev *dev, struct synaptics_data *priv)
>>        }
>>
>>        if (SYN_CAP_PALMDETECT(priv->capabilities))
>> -               input_set_abs_params(dev, ABS_TOOL_WIDTH, 0, 15, 0, 0);
>> +               input_set_abs_params(dev, ABS_TOOL_WIDTH, 4, 15, 0, 0);
>>
>>        __set_bit(EV_KEY, dev->evbit);
>>        __set_bit(BTN_TOUCH, dev->keybit);
>> --
>> 1.7.3.1
>>
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