linux-kernel - Re: [PATCH] Input: of_touchscreen - remove interdependence of max/fuzz values

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Date:	Sat, 30 May 2015 08:26:51 +0200
From:	Pavel Machek <pavel@....cz>
To:	Sebastian Reichel <sre@...nel.org>
Cc:	dmitry.torokhov@...il.com, maxime.ripard@...e-electrons.com,
	kernel list <linux-kernel@...r.kernel.org>,
	linux-omap@...r.kernel.org, linux-input@...r.kernel.org
Subject: Re: [PATCH] Input: of_touchscreen - remove interdependence of
 max/fuzz values

On Sat 2015-05-30 04:24:34, Sebastian Reichel wrote:
> Commit 3eea8b5d68c8 introduced a dependency between touchscreen-max-*
> and touchscreen-fuzz-*, so that either both must be specified or none
> of them. If only one of them is specified the other value will be
> reset to 0. This commit restores the previous behaviour, that the
> drivers default value will be used for the unspecified value.
> 
> Reported-By: Pavel Machek <pavel@....cz>
> Fixes: 3eea8b5d68c8 (Input: of_touchscreen - rework the DT parsing function)
> Signed-off-by: Sebastian Reichel <sre@...nel.org>
> ---
>  drivers/input/touchscreen/of_touchscreen.c | 25 +++++++++++--------------
>  1 file changed, 11 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/of_touchscreen.c b/drivers/input/touchscreen/of_touchscreen.c
> index b82b520..7d2cf59 100644
> --- a/drivers/input/touchscreen/of_touchscreen.c
> +++ b/drivers/input/touchscreen/of_touchscreen.c
> @@ -42,8 +42,11 @@ static void touchscreen_set_params(struct input_dev *dev,
>  	}
>  
>  	absinfo = &dev->absinfo[axis];
> -	absinfo->maximum = max;
> -	absinfo->fuzz = fuzz;
> +
> +	if (max)
> +		absinfo->maximum = max;
> +	if (fuzz)
> +		absinfo->fuzz = fuzz;

If driver sets absinfo->fuzz to 5, and then device tree specifies fuzz
of 0, this means it will not be overwritten.

> @@ -65,23 +68,17 @@ void touchscreen_parse_of_params(struct input_dev *dev)
>  
>  	maximum = of_get_optional_u32(np, "touchscreen-size-x");
>  	fuzz = of_get_optional_u32(np, "touchscreen-fuzz-x");
> -	if (maximum || fuzz) {
> -		touchscreen_set_params(dev, ABS_X, maximum, fuzz);
> -		touchscreen_set_params(dev, ABS_MT_POSITION_X, maximum, fuzz);
> -	}
> +	touchscreen_set_params(dev, ABS_X, maximum, fuzz);
> +	touchscreen_set_params(dev, ABS_MT_POSITION_X, maximum, fuzz);

This will introduce warn_on() on axis that are not mentioned in the
device tree. Same problem Dmitry did not like on my patch.
								Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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