linux-kernel - Re: [PATCH RFC v4 5/6] ARM: pxa: Convert gumstix Bluetooth to GPIO descriptors

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Message-ID: <CAMRc=MdHv0YxSowMnqJ8xG1_w8dwTWVJV1K0b1jgectPTbOheQ@mail.gmail.com>
Date:   Mon, 2 Oct 2023 09:42:52 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Duje Mihanović <duje.mihanovic@...le.hr>
Cc:     Daniel Mack <daniel@...que.org>,
        Haojian Zhuang <haojian.zhuang@...il.com>,
        Robert Jarzmik <robert.jarzmik@...e.fr>,
        Russell King <linux@...linux.org.uk>,
        Alan Stern <stern@...land.harvard.edu>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Andy Shevchenko <andy@...nel.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        Mark Brown <broonie@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-usb@...r.kernel.org, linux-gpio@...r.kernel.org,
        linux-input@...r.kernel.org, linux-spi@...r.kernel.org
Subject: Re: [PATCH RFC v4 5/6] ARM: pxa: Convert gumstix Bluetooth to GPIO descriptors

On Sun, Oct 1, 2023 at 4:13 PM Duje Mihanović <duje.mihanovic@...le.hr> wrote:
>
> Gumstix still uses the legacy GPIO interface for resetting the Bluetooth
> device.
>
> Convert it to use the GPIO descriptor interface.
>
> Reviewed-by: Linus Walleij <linus.walleij@...aro.org>
> Signed-off-by: Duje Mihanović <duje.mihanovic@...le.hr>
> ---
>  arch/arm/mach-pxa/gumstix.c | 24 +++++++++++++-----------
>  1 file changed, 13 insertions(+), 11 deletions(-)
>
> diff --git a/arch/arm/mach-pxa/gumstix.c b/arch/arm/mach-pxa/gumstix.c
> index c9f0f62187bd..14e1b9274d7a 100644
> --- a/arch/arm/mach-pxa/gumstix.c
> +++ b/arch/arm/mach-pxa/gumstix.c
> @@ -20,8 +20,8 @@
>  #include <linux/delay.h>
>  #include <linux/mtd/mtd.h>
>  #include <linux/mtd/partitions.h>
> +#include <linux/gpio/consumer.h>
>  #include <linux/gpio/machine.h>
> -#include <linux/gpio.h>
>  #include <linux/err.h>
>  #include <linux/clk.h>
>
> @@ -129,6 +129,9 @@ static void gumstix_udc_init(void)
>  #endif
>
>  #ifdef CONFIG_BT
> +GPIO_LOOKUP_SINGLE(gumstix_bt_gpio_table, "pxa2xx-uart.1", "pxa-gpio",
> +               GPIO_GUMSTIX_BTRESET, "BTRST", GPIO_ACTIVE_LOW);
> +
>  /* Normally, the bootloader would have enabled this 32kHz clock but many
>  ** boards still have u-boot 1.1.4 so we check if it has been turned on and
>  ** if not, we turn it on with a warning message. */
> @@ -153,24 +156,23 @@ static void gumstix_setup_bt_clock(void)
>
>  static void __init gumstix_bluetooth_init(void)
>  {
> -       int err;
> +       struct gpio_desc *desc;
> +
> +       gpiod_add_lookup_table(&gumstix_bt_gpio_table);
>
>         gumstix_setup_bt_clock();
>
> -       err = gpio_request(GPIO_GUMSTIX_BTRESET, "BTRST");
> -       if (err) {
> +       desc = gpiod_get(&pxa_device_btuart.dev, "BTRST", GPIOD_OUT_HIGH);
> +       if (IS_ERR(desc)) {
>                 pr_err("gumstix: failed request gpio for bluetooth reset\n");
>                 return;
>         }
>
> -       err = gpio_direction_output(GPIO_GUMSTIX_BTRESET, 1);
> -       if (err) {
> -               pr_err("gumstix: can't reset bluetooth\n");
> -               return;
> -       }
> -       gpio_set_value(GPIO_GUMSTIX_BTRESET, 0);
> +       gpiod_set_value(desc, 0);
>         udelay(100);
> -       gpio_set_value(GPIO_GUMSTIX_BTRESET, 1);
> +       gpiod_set_value(desc, 1);
> +
> +       gpiod_put(desc);

This changes the way this code works. You release the descriptor here,
it returns to the driver and can be re-requested by someone else. Its
value is also not guaranteed to remain as "active". Is this what you
want?

Bart

>  }
>  #else
>  static void gumstix_bluetooth_init(void)
>
> --
> 2.42.0
>
>