linux-kernel - Re: [PATCH] pinctrl: Really force states during suspend/resume

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Message-ID: <CAHp75VejE9ofBBSbKraon96pWDg7a00TJgViS-m6BGO4p0_E8A@mail.gmail.com>
Date:   Wed, 8 Feb 2017 23:46:20 +0200
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Florian Fainelli <f.fainelli@...il.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Al Cooper <alcooperx@...il.com>, swarren@...dia.com,
        "open list:PIN CONTROL SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] pinctrl: Really force states during suspend/resume

On Wed, Feb 8, 2017 at 3:17 AM, Florian Fainelli <f.fainelli@...il.com> wrote:
> In case a platform only defaults a "default" set of pins, but not a
> "sleep" set of pins, and this particular platform suspends and resumes
> in a way that the pin states are not preserved by the hardware, when we
> resume, we would call pinctrl_single_resume() -> pinctrl_force_default()
> -> pinctrl_select_state() and the first thing we do is check that the
> pins state is the same as before, and do nothing.
>
> In order to fix this, decouple pinctrl_select_state and make it become
> __pinctrl_select_state(), taking an additional ignore_state_check
> boolean which allows us to bypass the state check during suspend/resume,
> since we really want to re-apply the previous pin states in these case.
>
> Fixes: 6e5e959dde0d ("pinctrl: API changes to support multiple states per device")
> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
> ---
> Linus,
>
> This is against your "fixes" branch, thank you!

Btw, I have got similar issue and thinking about those states they are
quite orthogonal to the pin states. Wouldn't be better to actually
differentiate PM related states and pin states?

In my case I have a ->probe() function where device is requested GPIO
in order to make it wake capable source without using anywhere else.
So, this requires to have "init" state to be defined which is kinda
inconvenient.

On resume/suspend it calls pinctrl_pm_state*() and requires "default"
and "sleep" states to be defined.

I think GPIO case is quite generic and pin control framework lacks of
something like switching some pins of the group to GPIO state and back
whenever they defined as wake capable sources.

I would work towards fixing this issue anyway (to get UART runtime PM
working on serial consoles).

>
>  drivers/pinctrl/core.c | 26 +++++++++++++++++++++-----
>  1 file changed, 21 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
> index fb38e208f32d..8b8017dc9e15 100644
> --- a/drivers/pinctrl/core.c
> +++ b/drivers/pinctrl/core.c
> @@ -992,17 +992,21 @@ struct pinctrl_state *pinctrl_lookup_state(struct pinctrl *p,
>  EXPORT_SYMBOL_GPL(pinctrl_lookup_state);
>
>  /**
> - * pinctrl_select_state() - select/activate/program a pinctrl state to HW
> + * __pinctrl_select_state() - select/activate/program a pinctrl state to HW
>   * @p: the pinctrl handle for the device that requests configuration
>   * @state: the state handle to select/activate/program
> + * @force: ignore the state check (e.g: to re-apply default state during
> + * suspend/resume)
>   */
> -int pinctrl_select_state(struct pinctrl *p, struct pinctrl_state *state)
> +static int __pinctrl_select_state(struct pinctrl *p,
> +                                 struct pinctrl_state *state,
> +                                 bool ignore_state_check)
>  {
>         struct pinctrl_setting *setting, *setting2;
>         struct pinctrl_state *old_state = p->state;
>         int ret;
>
> -       if (p->state == state)
> +       if (p->state == state && !ignore_state_check)
>                 return 0;
>
>         if (p->state) {
> @@ -1068,6 +1072,16 @@ int pinctrl_select_state(struct pinctrl *p, struct pinctrl_state *state)
>
>         return ret;
>  }
> +
> +/**
> + * pinctrl_select_state() - select/activate/program a pinctrl state to HW
> + * @p: the pinctrl handle for the device that requests configuration
> + * @state: the state handle to select/activate/program
> + */
> +int pinctrl_select_state(struct pinctrl *p, struct pinctrl_state *state)
> +{
> +       return __pinctrl_select_state(p, state, false);
> +}
>  EXPORT_SYMBOL_GPL(pinctrl_select_state);
>
>  static void devm_pinctrl_release(struct device *dev, void *res)
> @@ -1236,7 +1250,8 @@ void pinctrl_unregister_map(struct pinctrl_map const *map)
>  int pinctrl_force_sleep(struct pinctrl_dev *pctldev)
>  {
>         if (!IS_ERR(pctldev->p) && !IS_ERR(pctldev->hog_sleep))
> -               return pinctrl_select_state(pctldev->p, pctldev->hog_sleep);
> +               return __pinctrl_select_state(pctldev->p,
> +                                             pctldev->hog_sleep, true);
>         return 0;
>  }
>  EXPORT_SYMBOL_GPL(pinctrl_force_sleep);
> @@ -1248,7 +1263,8 @@ EXPORT_SYMBOL_GPL(pinctrl_force_sleep);
>  int pinctrl_force_default(struct pinctrl_dev *pctldev)
>  {
>         if (!IS_ERR(pctldev->p) && !IS_ERR(pctldev->hog_default))
> -               return pinctrl_select_state(pctldev->p, pctldev->hog_default);
> +               return __pinctrl_select_state(pctldev->p,
> +                                             pctldev->hog_default, true);
>         return 0;
>  }
>  EXPORT_SYMBOL_GPL(pinctrl_force_default);
> --
> 2.9.3
>



-- 
With Best Regards,
Andy Shevchenko