Hi Clinton, > input: appletouch: implement sensor data smoothing > > Use smoothed version of sensor array data to calculate movement and add weight > to prior values when calculating average. This gives more granular and more > predictable movement. > > Signed-off-by: Clinton Sprain <[email protected]> > --- > drivers/input/mouse/appletouch.c | 72 > ++++++++++++++++++++++++++++---------- > 1 file changed, 53 insertions(+), 19 deletions(-) > > diff --git a/drivers/input/mouse/appletouch.c > b/drivers/input/mouse/appletouch.c > index 2745832..e00f126 100644 > --- a/drivers/input/mouse/appletouch.c > +++ b/drivers/input/mouse/appletouch.c > @@ -332,7 +332,11 @@ static void atp_reinit(struct work_struct *work) > static int atp_calculate_abs(int *xy_sensors, int nb_sensors, int fact, > int *z, int *fingers) > { > - int i; > + int i, k; > + int smooth[nb_sensors + 8]; > + int smooth_tmp[nb_sensors + 8]; > + int scale = 12; > + > /* values to calculate mean */ > int pcum = 0, psum = 0; > int is_increasing = 0; > @@ -344,9 +348,6 @@ static int atp_calculate_abs(int *xy_sensors, int > nb_sensors, int fact, > if (is_increasing) > is_increasing = 0; > > - continue; > - } > - > /* > * Makes the finger detection more versatile. For example, > * two fingers with no gap will be detected. Also, my > @@ -361,27 +362,60 @@ static int atp_calculate_abs(int *xy_sensors, int > nb_sensors, int fact, > * > * - Jason Parekh <[email protected]> > */ > - if (i < 1 || > + > + } else if (i < 1 || > (!is_increasing && xy_sensors[i - 1] < xy_sensors[i])) { > (*fingers)++; > is_increasing = 1; > } else if (i > 0 && (xy_sensors[i - 1] - xy_sensors[i] > > threshold)) { > is_increasing = 0; > } > + } > > - /* > - * Subtracts threshold so a high sensor that just passes the > - * threshold won't skew the calculated absolute coordinate. > - * Fixes an issue where slowly moving the mouse would > - * occasionally jump a number of pixels (slowly moving the > - * finger makes this issue most apparent.) > - */ > - pcum += (xy_sensors[i] - threshold) * i; > - psum += (xy_sensors[i] - threshold); > + /* > + * Use a smoothed version of sensor data for movement calculations, to > + * combat noise without needing to rely so heavily on a threshold. > + * This improves tracking. > + * > + * The smoothed array is bigger than the original so that the smoothing > + * doesn't result in edge values being truncated. > + */ > + > + for (i = 0; i < 4; i++) > + smooth[i] = 0; > + for (i = nb_sensors + 4; i < nb_sensors + 8; i++) > + smooth[i] = 0; > + > + /* Pull base values, scaled up to help avoid truncation errors. */ > + > + for (i = 0; i < nb_sensors; i++) > + smooth[i + 4] = xy_sensors[i] << scale; > + > + for (k = 0; k < 4; k++) { > + > + /* Handle edge. */ > + smooth_tmp[0] = (smooth[0] + smooth[1]) >> 1; > + > + /* Average values with neighbors. */ > + for (i = 1; i < nb_sensors + 7; i++) > + smooth_tmp[i] = (smooth[i - 1] + smooth[i] * 2 + > smooth[i + 1]) >> 2; > + > + /* Handle other edge. */ > + smooth_tmp[nb_sensors + 7] = (smooth[nb_sensors + 7] + > smooth[nb_sensors + 6]) >> 1; > + > + for (i = 0; i < nb_sensors + 8; i++) > + smooth[i] = smooth_tmp[i]; > + } > + > + for (i = 0; i < nb_sensors + 8; i++) { > + if ((smooth[i] >> scale) > 0) { /* Skip individual values if */ > + pcum += (smooth[i]) * i; /* they are small enough to */ > + psum += (smooth[i]); /* be truncated to 0 by our */ > + } /* scale; mostly just noise. */ > } > > if (psum > 0) { > - *z = psum; > + *z = psum >> scale; /* Scale down pressure output. */ > return pcum * fact / psum; > } > > @@ -559,8 +593,8 @@ static void atp_complete_geyser_1_2(struct urb *urb) > > if (x && y) { > if (dev->x_old != -1) { > - x = (dev->x_old * 3 + x) >> 2; > - y = (dev->y_old * 3 + y) >> 2; > + x = (dev->x_old * 7 + x) >> 3; > + y = (dev->y_old * 7 + y) >> 3; > dev->x_old = x; > dev->y_old = y; > > @@ -671,8 +705,8 @@ static void atp_complete_geyser_3_4(struct urb *urb) > > if (x && y) { > if (dev->x_old != -1) { > - x = (dev->x_old * 3 + x) >> 2; > - y = (dev->y_old * 3 + y) >> 2; > + x = (dev->x_old * 7 + x) >> 3; > + y = (dev->y_old * 7 + y) >> 3; > dev->x_old = x; > dev->y_old = y; > >
Reviewed-by: Henrik Rydberg <[email protected]> Thanks, Henrik -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
