linux-kernel - Re: [PATCH] spi: atmel: use managed resource for gpio chip select

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Message-ID: <CAMuHMdUQLkHn4=3U6TNjgTN--RUHZHsbwNu9dLdFrBJA0sx4aw@mail.gmail.com>
Date:   Wed, 21 Sep 2016 10:20:27 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Nicolas Ferre <nicolas.ferre@...el.com>
Cc:     linux@...tdown.ru, Mark Brown <broonie@...nel.org>,
        Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
        Boris BREZILLON <boris.brezillon@...e-electrons.com>,
        linux-spi <linux-spi@...r.kernel.org>,
        Ludovic Desroches <ludovic.desroches@...el.com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Cyrille Pitchen <cyrille.pitchen@...el.com>,
        Wenyou Yang <wenyou.yang@...el.com>
Subject: Re: [PATCH] spi: atmel: use managed resource for gpio chip select

Hi Nicolas,

On Wed, Sep 21, 2016 at 9:55 AM, Nicolas Ferre <nicolas.ferre@...el.com> wrote:
> Use the managed gpio CS pin request so that we avoid having trouble
> in the cleanup code.
> In fact, if module was configured with DT, cleanup code released
> invalid pin.  Since resource wasn't freed, module cannot be reinserted.
>
> Reported-by: Alexander Morozov <linux@...tdown.ru>
> Signed-off-by: Nicolas Ferre <nicolas.ferre@...el.com>
> ---
>  drivers/spi/spi-atmel.c | 5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/spi/spi-atmel.c b/drivers/spi/spi-atmel.c
> index 8feac599e9ab..4e3f2345844a 100644
> --- a/drivers/spi/spi-atmel.c
> +++ b/drivers/spi/spi-atmel.c
> @@ -1248,7 +1248,8 @@ static int atmel_spi_setup(struct spi_device *spi)
>                         return -ENOMEM;
>
>                 if (as->use_cs_gpios) {
> -                       ret = gpio_request(npcs_pin, dev_name(&spi->dev));
> +                       ret = devm_gpio_request(&spi->dev,
> +                                               npcs_pin, dev_name(&spi->dev));

Note that spi_master.setup() can be called multiple times during the lifetime
of the spi_device.

>                         if (ret) {
>                                 kfree(asd);
>                                 return ret;
> @@ -1471,13 +1472,11 @@ static int atmel_spi_transfer_one_message(struct spi_master *master,
>  static void atmel_spi_cleanup(struct spi_device *spi)
>  {
>         struct atmel_spi_device *asd = spi->controller_state;
> -       unsigned                gpio = (unsigned long) spi->controller_data;
>
>         if (!asd)
>                 return;
>
>         spi->controller_state = NULL;
> -       gpio_free(gpio);
>         kfree(asd);
>  }

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds