linux-kernel - Re: [PATCH v3] gpio: fxl6408: Add suspend/resume support

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Message-ID: <CAMRc=McxjLYDWzKFm4FzNkDR_Com=8ODc7DuvXihtbOR8mEFag@mail.gmail.com>
Date: Wed, 19 Nov 2025 14:41:28 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Jisheng Zhang <jszhang@...nel.org>
Cc: Linus Walleij <linus.walleij@...aro.org>, linux-gpio@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] gpio: fxl6408: Add suspend/resume support

On Wed, Nov 19, 2025 at 2:27 PM Jisheng Zhang <jszhang@...nel.org> wrote:
>
> Currently, during suspend, do nothing; during resume, just sync the
> regmap cache to hw regs.
>
> Signed-off-by: Jisheng Zhang <jszhang@...nel.org>
> ---
>
> since v2:
>   - drop the reset pin support patch since no users now
>
> since v1:
>   -fix W=1 build error on nios2 platform
>
>  drivers/gpio/gpio-fxl6408.c | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
>
> diff --git a/drivers/gpio/gpio-fxl6408.c b/drivers/gpio/gpio-fxl6408.c
> index 86ebc66b1104..165c48e9cb9c 100644
> --- a/drivers/gpio/gpio-fxl6408.c
> +++ b/drivers/gpio/gpio-fxl6408.c
> @@ -43,6 +43,10 @@
>
>  #define FXL6408_NGPIO                  8
>
> +struct fxl6408_chip {
> +       struct regmap *regmap;
> +};

I would simplify the patch by roughly 50% by dropping this wrapper
structure. I know it's less future-proof but it doesn't seem that
we'll need more fields here anytime soon. We can cross that bridge
when we get there.

> +
>  static const struct regmap_range rd_range[] = {
>         { FXL6408_REG_DEVICE_ID, FXL6408_REG_DEVICE_ID },
>         { FXL6408_REG_IO_DIR, FXL6408_REG_OUTPUT },
> @@ -104,6 +108,7 @@ static int fxl6408_identify(struct device *dev, struct regmap *regmap)
>  static int fxl6408_probe(struct i2c_client *client)
>  {
>         struct device *dev = &client->dev;
> +       struct fxl6408_chip *chip;
>         int ret;
>         struct gpio_regmap_config gpio_config = {
>                 .parent = dev,
> @@ -114,6 +119,10 @@ static int fxl6408_probe(struct i2c_client *client)
>                 .ngpio_per_reg = FXL6408_NGPIO,
>         };
>
> +       chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
> +       if (!chip)
> +               return -ENOMEM;

That would go away.

> +
>         gpio_config.regmap = devm_regmap_init_i2c(client, &regmap);
>         if (IS_ERR(gpio_config.regmap))
>                 return dev_err_probe(dev, PTR_ERR(gpio_config.regmap),
> @@ -123,6 +132,9 @@ static int fxl6408_probe(struct i2c_client *client)
>         if (ret)
>                 return ret;
>
> +       chip->regmap = gpio_config.regmap;

That too.

> +       i2c_set_clientdata(client, chip);

You'd just do i2c_set_clientdata(client, gpio_config.regmap) here.

> +
>         /* Disable High-Z of outputs, so that our OUTPUT updates actually take effect. */
>         ret = regmap_write(gpio_config.regmap, FXL6408_REG_OUTPUT_HIGH_Z, 0);
>         if (ret)
> @@ -131,6 +143,16 @@ static int fxl6408_probe(struct i2c_client *client)
>         return PTR_ERR_OR_ZERO(devm_gpio_regmap_register(dev, &gpio_config));
>  }
>
> +static int fxl6408_resume(struct device *dev)
> +{
> +       struct fxl6408_chip *chip = dev_get_drvdata(dev);
> +
> +       regcache_mark_dirty(chip->regmap);
> +       return regcache_sync(chip->regmap);
> +}
> +
> +static DEFINE_SIMPLE_DEV_PM_OPS(fxl6408_pm_ops, NULL, fxl6408_resume);
> +
>  static const __maybe_unused struct of_device_id fxl6408_dt_ids[] = {
>         { .compatible = "fcs,fxl6408" },
>         { }
> @@ -146,6 +168,7 @@ MODULE_DEVICE_TABLE(i2c, fxl6408_id);
>  static struct i2c_driver fxl6408_driver = {
>         .driver = {
>                 .name   = "fxl6408",
> +               .pm     = pm_sleep_ptr(&fxl6408_pm_ops),
>                 .of_match_table = fxl6408_dt_ids,
>         },
>         .probe          = fxl6408_probe,
> --
> 2.51.0
>

Bart