linux-kernel - Re: [PATCH V2] mmc: pwrseq_simple: Handle !RESET

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Message-ID: <CAPDyKFrKTw16mfmMcnaz08vPJsAsC6KJj_j8j6UcbQif9VK1cA@mail.gmail.com>
Date: Tue, 12 Nov 2024 19:43:54 +0100
From: Ulf Hansson <ulf.hansson@...aro.org>
To: Stefan Wahren <wahrenst@....net>
Cc: Philipp Zabel <p.zabel@...gutronix.de>, Marco Felsch <m.felsch@...gutronix.de>, 
	Catalin Popescu <catalin.popescu@...ca-geosystems.com>, 
	Florian Fainelli <florian.fainelli@...adcom.com>, linux-arm-kernel@...ts.infradead.org, 
	linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2] mmc: pwrseq_simple: Handle !RESET_CONTROLLER properly

On Fri, 8 Nov 2024 at 14:06, Stefan Wahren <wahrenst@....net> wrote:
>
> The recent introduction of reset control in pwrseq_simple introduced
> a regression for platforms without RESET_CONTROLLER support, because
> devm_reset_control_get_optional_shared() would return NULL and make all
> resets no-ops. Instead of enforcing this dependency, rely on this behavior
> to determine reset support. As a benefit we can get the rid of the
> use_reset flag.
>
> Fixes: 73bf4b7381f7 ("mmc: pwrseq_simple: add support for one reset control")
> Signed-off-by: Stefan Wahren <wahrenst@....net>

Applied for next, thanks!

Kind regards
Uffe


> ---
>  drivers/mmc/core/pwrseq_simple.c | 20 +++++++++++---------
>  1 file changed, 11 insertions(+), 9 deletions(-)
>
> Changes in V2:
> - add explaining comment as suggested by Marco Felsch
>
> diff --git a/drivers/mmc/core/pwrseq_simple.c b/drivers/mmc/core/pwrseq_simple.c
> index 24e4e63a5dc8..37cd858df0f4 100644
> --- a/drivers/mmc/core/pwrseq_simple.c
> +++ b/drivers/mmc/core/pwrseq_simple.c
> @@ -32,7 +32,6 @@ struct mmc_pwrseq_simple {
>         struct clk *ext_clk;
>         struct gpio_descs *reset_gpios;
>         struct reset_control *reset_ctrl;
> -       bool use_reset;
>  };
>
>  #define to_pwrseq_simple(p) container_of(p, struct mmc_pwrseq_simple, pwrseq)
> @@ -71,7 +70,7 @@ static void mmc_pwrseq_simple_pre_power_on(struct mmc_host *host)
>                 pwrseq->clk_enabled = true;
>         }
>
> -       if (pwrseq->use_reset) {
> +       if (pwrseq->reset_ctrl) {
>                 reset_control_deassert(pwrseq->reset_ctrl);
>                 reset_control_assert(pwrseq->reset_ctrl);
>         } else
> @@ -82,7 +81,7 @@ static void mmc_pwrseq_simple_post_power_on(struct mmc_host *host)
>  {
>         struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
>
> -       if (pwrseq->use_reset)
> +       if (pwrseq->reset_ctrl)
>                 reset_control_deassert(pwrseq->reset_ctrl);
>         else
>                 mmc_pwrseq_simple_set_gpios_value(pwrseq, 0);
> @@ -95,7 +94,7 @@ static void mmc_pwrseq_simple_power_off(struct mmc_host *host)
>  {
>         struct mmc_pwrseq_simple *pwrseq = to_pwrseq_simple(host->pwrseq);
>
> -       if (pwrseq->use_reset)
> +       if (pwrseq->reset_ctrl)
>                 reset_control_assert(pwrseq->reset_ctrl);
>         else
>                 mmc_pwrseq_simple_set_gpios_value(pwrseq, 1);
> @@ -137,15 +136,18 @@ static int mmc_pwrseq_simple_probe(struct platform_device *pdev)
>                 return dev_err_probe(dev, PTR_ERR(pwrseq->ext_clk), "external clock not ready\n");
>
>         ngpio = of_count_phandle_with_args(dev->of_node, "reset-gpios", "#gpio-cells");
> -       if (ngpio == 1)
> -               pwrseq->use_reset = true;
> -
> -       if (pwrseq->use_reset) {
> +       if (ngpio == 1) {
>                 pwrseq->reset_ctrl = devm_reset_control_get_optional_shared(dev, NULL);
>                 if (IS_ERR(pwrseq->reset_ctrl))
>                         return dev_err_probe(dev, PTR_ERR(pwrseq->reset_ctrl),
>                                              "reset control not ready\n");
> -       } else {
> +       }
> +
> +       /*
> +        * Fallback to GPIO based reset control in case of multiple reset lines
> +        * are specified or the platform doesn't have support for RESET at all.
> +        */
> +       if (!pwrseq->reset_ctrl) {
>                 pwrseq->reset_gpios = devm_gpiod_get_array(dev, "reset", GPIOD_OUT_HIGH);
>                 if (IS_ERR(pwrseq->reset_gpios) &&
>                     PTR_ERR(pwrseq->reset_gpios) != -ENOENT &&
> --
> 2.34.1
>