Hi Henrik,
Thanks for your comments.
> >>> +static bool bu21013_verify_delta(int x1, int y1, int x2, int y2)
> >>> +{
> >>> + int delta_x, delta_y;
> >>> +
> >>> + if ((x1 != 0) && (y1 != 0)) {
> >>> + delta_x = x2 - x1;
> >>> + if (x1 > x2)
> >>> + delta_x = x1 - x2;
> >>> + delta_y = y2 - y1;
> >>> + if (y1 > y2)
> >>> + delta_y = y1 - y2;
> >>> + if ((delta_x < DELTA_MIN) || (delta_y < DELTA_MIN))
> >>> + return false;
> >>> + }
> >>> + return true;
> >>
> >> Hmm, I remember - the fuzz handling indeed will not work for MT A
> protocol.
> >> Still, I do not think it is correct. Don't you need to do
> >> "abs(delta_x) < DELTA_MIN"?
>
>
> True, fuzz wont be processed in the kernel, but the information can be
> used
> outside the kernel, like in mtdev.
>
> I do not understand why deltas are verified in the first place. Either
> one can
> rely on the identity of the fingers, in which case MT slots is simpler
> to
> handle, or one cannot rely on it, in which case the above code is
> wrong, since
> it assumes the values compared have the same identity.
>
This case according to controller specification, when the two fingers delta is of
16 either in x or y, we should ignore those co-ordinates and report as pen-up.
> Perhaps the logic could be inverted so that the case when the total
> number is
> zero is treated first, to avoid repeated tests below.
>
> >>> + if ((finger2_pos_x != 0) && (finger2_pos_y != 0)) {
> >>> + if ((finger1_pos_x == 0) || (finger1_pos_y
> == 0))
> >>> + return 0;
>
>
> So zero is some kind of null value? No continuation here?
>
> >>> + ret = bu21013_verify_delta(finger1_pos_x,
> >>> + finger1_pos_y, finger2_pos_x,
> finger2_pos_y);
> >>> + if (!ret)
> >>> + total_number_of_active_sensors = 0;
> >>> + }
>
>
> So this is a tracking-plus-filtering solution? Unless the form factor
> forbids
> it, having driver-specific tracking solutions in the kernel is not
> encouraged.
> Two fingers might be borderline.
We need to keep this filtering solution according to the controller specification.
Thanks & Regards,
Naveen
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