Re: [PATCH 2/5] Input: zinitix - do not ignore non-moving fingers

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Hi Kaustabh,

On Fri, Jul 24, 2026 at 12:54:04AM +0530, Kaustabh Chakraborty wrote:
> With the ZT7548 touchscreen present in the Galaxy J6, multitouch does not
> work reliably. This is due to the fact that the driver reports fingers
> only when their state is changed, so it's either placed against the
> scren, moved, or drawn away from the screen.
> 
> The function which is responsible for this is zinitix_report_finger().
> This function is called from the IRQ handler, under the following
> condition:
> 
> 		if (p->sub_status & SUB_BIT_EXIST)
> 			zinitix_report_finger(bt541, i, p);
> 
> This implies and ensures that every valid finger must have the
> SUB_BIT_EXIST flag.
> 
> However, at the beginning of the function, it refuses to recognize any
> finger if it has none of SUB_BIT_UP | SUB_BIT_DOWN | SUB_BIT_MOVE. This
> excludes fingers in reports which do not move from the position since
> the previous interrupt. Add SUB_BIT_EXIST to the list of valid bits.

This makes the check basically a no-op as SUB_BIT_EXIST would always be
set when we reach this function. It may very well be that we want to
delete this check altogether, or maybe we need to add SUB_BIT_UPDATE and
SUB_BIT_WAIT. I am curious what status bits you see when this condition
(original) triggers for you...

> 
> Signed-off-by: Kaustabh Chakraborty <kauschluss@disroot.org>
> ---
>  drivers/input/touchscreen/zinitix.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/input/touchscreen/zinitix.c b/drivers/input/touchscreen/zinitix.c
> index 3421b8ffb19b..fdcb80f52c91 100644
> --- a/drivers/input/touchscreen/zinitix.c
> +++ b/drivers/input/touchscreen/zinitix.c
> @@ -406,7 +406,7 @@ static void zinitix_report_finger(struct bt541_ts_data *bt541, int slot,
>  	u16 x, y;
>  
>  	if (unlikely(!(p->sub_status &
> -		       (SUB_BIT_UP | SUB_BIT_DOWN | SUB_BIT_MOVE)))) {
> +		       (SUB_BIT_EXIST | SUB_BIT_UP | SUB_BIT_DOWN | SUB_BIT_MOVE)))) {
>  		dev_dbg(&bt541->client->dev, "unknown finger event %#02x\n",
>  			p->sub_status);
>  		return;
> 

Thanks.

-- 
Dmitry