On Mon, Jan 24, 2011 at 6:40 AM, Henrik Rydberg <rydberg@xxxxxxxxxxx> wrote:
> Hi Ping,
>
>> @@ -1228,8 +1228,13 @@ void wacom_setup_input_capabilities(struct input_dev *input_dev,
>> case TABLETPC:
>> if (features->device_type == BTN_TOOL_DOUBLETAP ||
>> features->device_type == BTN_TOOL_TRIPLETAP) {
>> - input_set_abs_params(input_dev, ABS_RX, 0, features->x_phy, 0, 0);
>> - input_set_abs_params(input_dev, ABS_RY, 0, features->y_phy, 0, 0);
>> + /* set touch resolution in points/mm */
>> + res = features->x_phy/100;
>> + input_abs_set_res(input_dev, ABS_X,
>> + features->x_max/res);
>
> It seems to me the construction above looses precision twice for no
> apparent reason.
Well, there was a reason (logically instead of mathematically though):
features->x_phy/100 gives us the physical size of the touch area in
mm.
> How about instead use "100 * features->x_max /
> features->x_phy"?
Sure.
> Besides, it is a bit unfortunate that "res" is short
> for both result and resolution.
Resolution is defined as __s32 in input_absinfo. How about we use __s32 then?
> Finally, are the physical dimensions
> actually presented in 100ths of millimeters?
Well, the protocol says it is in thousandth of a centimeter. So, 100th
of a mm is right too.
Thank you for the comments.
Ping
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