On Mon, Jan 24, 2011 at 10:18:54AM -0800, Ping Cheng wrote:
> 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?
input_abs_set_res() takes and int argument so keep it int (or just
embed the expression into the call and forgo 'res').
--
Dmitry
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