linux-kernel - Re: [PATCH] Input: synaptics-rmi4: Limit the range of what GPIOs are buttons

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Message-ID: <20171025133735.GH13605@mail.corp.redhat.com>
Date:   Wed, 25 Oct 2017 15:37:35 +0200
From:   Benjamin Tissoires <benjamin.tissoires@...hat.com>
To:     Andrew Duggan <aduggan@...aptics.com>
Cc:     linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Daniel Martin <consume.noise@...il.com>,
        Hendrik Langer <hendrik.langer@....de>
Subject: Re: [PATCH] Input: synaptics-rmi4: Limit the range of what GPIOs are
 buttons

On Oct 24 2017 or thereabouts, Andrew Duggan wrote:
> By convention the first 6 bits of F30 Ctrl 2 and 3 are used to signify

I really do not like the "by convention". What if future firmware
developers are willing to add extra buttons and already have trackstick
buttons there, meaning the max 6 button count will be blown up? :/

Still, there is not much we can do (or have a whitelist, but it is a
pain), so:
Acked-By: Benjamin Tissoires <benjamin.tissoires@...hat.com>

Cheers,
Benjamin

> GPIOs which are connected to buttons. Additional GPIOs may be used as
> input GPIOs to signal the touch controller of some event
> (ie disable touchpad). These additional GPIOs may meet the criteria of
> a button in rmi_f30_is_valid_button() but should not be considered
> buttons. This patch limits the GPIOs which are mapped to buttons to just
> the first 6.
> 
> Signed-off-by: Andrew Duggan <aduggan@...aptics.com>
> Reported-by: Daniel Martin <consume.noise@...il.com>
> ---
> I think that this patch will fix the issue with the Lenovo X1 Cover not
> being set as a buttonpad. Based on the firmware config for this touchpad
> there are additional GPIOs in Ctrl 2 and 3 position 6 and 7 unrelated to
> buttons. This is confusing F30 into thinking there are additional buttons.
> 
> https://www.spinics.net/lists/linux-input/msg53626.html
> 
>  drivers/input/rmi4/rmi_f30.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/input/rmi4/rmi_f30.c b/drivers/input/rmi4/rmi_f30.c
> index 34dfee5..a8ed424 100644
> --- a/drivers/input/rmi4/rmi_f30.c
> +++ b/drivers/input/rmi4/rmi_f30.c
> @@ -232,9 +232,11 @@ static int rmi_f30_map_gpios(struct rmi_function *fn,
>  	unsigned int trackstick_button = BTN_LEFT;
>  	bool button_mapped = false;
>  	int i;
> +	int button_count = f30->gpioled_count > TRACKSTICK_RANGE_END
> +				? TRACKSTICK_RANGE_END : f30->gpioled_count;
>  
>  	f30->gpioled_key_map = devm_kcalloc(&fn->dev,
> -					    f30->gpioled_count,
> +					    button_count,
>  					    sizeof(f30->gpioled_key_map[0]),
>  					    GFP_KERNEL);
>  	if (!f30->gpioled_key_map) {
> @@ -242,7 +244,7 @@ static int rmi_f30_map_gpios(struct rmi_function *fn,
>  		return -ENOMEM;
>  	}
>  
> -	for (i = 0; i < f30->gpioled_count; i++) {
> +	for (i = 0; i < button_count; i++) {
>  		if (!rmi_f30_is_valid_button(i, f30->ctrl))
>  			continue;
>  
> -- 
> 2.7.4
>