linux-kernel - Re: [PATCH v1 36/63] Input: atmel_mxt_ts - configure and use gpios as real gpios

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Message-ID: <20190816172422.GH121898@dtor-ws>
Date:   Fri, 16 Aug 2019 10:24:22 -0700
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Jiada Wang <jiada_wang@...tor.com>
Cc:     nick@...anahar.org, linux-input@...r.kernel.org,
        linux-kernel@...r.kernel.org, george_davis@...tor.com
Subject: Re: [PATCH v1 36/63] Input: atmel_mxt_ts - configure and use gpios
 as real gpios

On Fri, Aug 16, 2019 at 05:34:58PM +0900, Jiada Wang wrote:
> From: Kautuk Consul <kautuk_consul@...tor.com>
> 
> The upstream Atmel mXT driver implementation seems to handle the
> T19 GPIO/PWM object as a key pad. Keys can be defined in the
> device tree ("linux,gpio-keymap") and will be transported as key
> events to the Linux input device if GPIO state changes.
> 
> With our hardware, the GPIO pins of the touch controller are
> connected to a PWM/backlight controller and used as supervision
> inputs. We like to read the status of the pins by a script or an
> application in the sysfs.
> 
> Adding newer sysfs entries which shall be placed in the input
> class directory eg:
> /sys/class/input/input<n>/backlight_error1

No, if you want to export GPIO lines for external use create a gpiochip
instance and register it with GPIO subsystem. No ad-hoc sysfs please.

Thanks.

-- 
Dmitry