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From:   Bartosz Golaszewski <bgolaszewski@baylibre.com>
Date:   Fri, 22 May 2020 17:02:19 +0200
Message-ID: <CAMpxmJXwS21ByzGTsZf6MC-ar-ajUeCCxzP-vNrBEWSLKD9+sw@mail.gmail.com>
Subject: Re: [PATCH] gpio: gpio-max730x: bring gpiochip_add_data after port config
To:     Rodrigo Alencar <455.rodrigo.alencar@gmail.com>
Cc:     linux-gpio <linux-gpio@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Linus Walleij <linus.walleij@linaro.org>,
        Rodrigo Alencar <alencar.fmce@imbel.gov.br>
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czw., 14 maj 2020 o 15:00 Rodrigo Alencar
<455.rodrigo.alencar@gmail.com> napisa=C5=82(a):
>
> gpiochip_add_data being called before might cause premature calls of
> the gpiochip operations before the port_config values are initialized,
> which would possibily write zeros to port gonfiguration registers,
> an operation not allowed. For example, if there are gpio-hog nodes
> in a device-tree, the sequence of function calls are performed
>
> gpiochip_add_data
> of_gpiochip_add
> of_gpiochip_scan_gpios
> of_gpiochip_add_hog
> gpiod_hog
> gpiochip_request_own_desc
> gpiod_configure_flags
> gpiod_direction_output/gpiod_direction_input
>
> which would call later the gpiochip operation direction_output or
> direction_input prior the port_config[] initialization.
>
> Moreover, gpiochip_get_data is replaced by the container_of macro
> inside the gpiochip operations, which would allow the calling of
> max7301_direction_input prior to gpiochip_add_data
>
> Signed-off-by: Rodrigo Alencar <455.rodrigo.alencar@gmail.com>

Applied with some tweaks to the commit message.

Bartosz