Re: [PATCH] driver:st1633: fixed multitouch incorrect coordinates

[Martin Kepplinger]

Am 19.08.2019 12:08 schrieb Dixit Parmar:
> From: Dixit Parmar <dixitparmar19@xxxxxxxxx>
>
> For Sitronix st1633 multi-touch controller driver the co-ordinates 
> reported
> for multiple fingers were wrong.
>
> So the below mentioned bug was filed,
> Bugzilla Bug ID: 204561
>
> While reading co-ordinates from specified I2C registers, the X & Y
> co-ordinates should be read from proper I2C address for particular 
> finger as
> specified in chip specific datasheet.
>
> for single touch this logic is working fine. However, for multi-touch
> scenario the logic of reading data from data buffer has issues.
>
> This patch fixes the reading logic from data buffer.
>
> Previous logic:
> * Offset of X & Y Lower byte coordinate is increased by i no. only(by 1 
> Byte)
>   for each finger.
>
> New logic:
> * The logic of reading X & Y Lower Byte coordinate needs to be 
> increased
>   by i+y for each time/finger.
>
> Signed-off-by: Dixit Parmar <dixitparmar19@xxxxxxxxx>
> ---
>  drivers/input/touchscreen/st1232.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/input/touchscreen/st1232.c
> b/drivers/input/touchscreen/st1232.c
> index 3492339..1139714 100644
> --- a/drivers/input/touchscreen/st1232.c
> +++ b/drivers/input/touchscreen/st1232.c
> @@ -81,8 +81,10 @@ static int st1232_ts_read_data(struct st1232_ts_data 
> *ts)
>  	for (i = 0, y = 0; i < ts->chip_info->max_fingers; i++, y += 3) {
>  		finger[i].is_valid = buf[i + y] >> 7;
>  		if (finger[i].is_valid) {
> -			finger[i].x = ((buf[i + y] & 0x0070) << 4) | buf[i + 1];
> -			finger[i].y = ((buf[i + y] & 0x0007) << 8) | buf[i + 2];
> +			finger[i].x = ((buf[i + y] & 0x0070) << 4) |
> +					buf[i + y + 1];
> +			finger[i].y = ((buf[i + y] & 0x0007) << 8) |
> +					buf[i + y + 2];

Seems like you're right. It's simply +1 (for x) and +2 (for y) from the 
high-byte locations.
Not sure how that went wrong.

Thank you,

Reviewed-by: Martin Kepplinger <martink@xxxxxxxxx>


>  			/* st1232 includes a z-axis / touch strength */
>  			if (ts->chip_info->have_z)