linux-kernel - Re: [PATCH] Input: ads7846 - don't set ABS

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Date:   Thu, 27 Jul 2023 13:39:16 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Benjamin Bara <bbara93@...il.com>
Cc:     linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
        Benjamin Bara <benjamin.bara@...data.com>
Subject: Re: [PATCH] Input: ads7846 - don't set ABS_PRESSURE when min == max

Hi Benjamin,

On Thu, Jul 27, 2023 at 05:19:57PM +0200, Benjamin Bara wrote:
> From: Benjamin Bara <benjamin.bara@...data.com>
> 
> When the optional fields "pressure_min" and "pressure_max" are not set,
> both fall back to 0, which results to the following libinput error:
> 
> ADS7846 Touchscreen: kernel bug: device has min == max on ABS_PRESSURE
> 
> Avoid it by only setting ABS_PRESSURE if the values differ.

What is the benefit of silently continuing without reporting pressure on
models that do support pressure readings, vs. using libinput's errors as
signal to adjust DT?

> 
> Signed-off-by: Benjamin Bara <benjamin.bara@...data.com>
> ---
>  drivers/input/touchscreen/ads7846.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
> index faea40dd66d0..2535424a5630 100644
> --- a/drivers/input/touchscreen/ads7846.c
> +++ b/drivers/input/touchscreen/ads7846.c
> @@ -1281,7 +1281,7 @@ static int ads7846_probe(struct spi_device *spi)
>  			pdata->y_min ? : 0,
>  			pdata->y_max ? : MAX_12BIT,
>  			0, 0);
> -	if (ts->model != 7845)
> +	if (ts->model != 7845 && pdata->pressure_min != pdata->pressure_max)
>  		input_set_abs_params(input_dev, ABS_PRESSURE,
>  				pdata->pressure_min, pdata->pressure_max, 0, 0);
>  
> 
> ---
> base-commit: 451cc82bd11eb6a374f4dbcfc1cf007eafea91ab
> change-id: 20230727-ads7846-pressure-05edfb01887f
> 
> Best regards,
> -- 
> Benjamin Bara <benjamin.bara@...data.com>
> 

Thanks.

-- 
Dmitry