linux-kernel - Re: [PATCH fixes v3] pinctrl: Really force states during suspend/resume

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Message-ID: <304fb86d-0862-992b-4563-61151b37d060@gmail.com>
Date:   Thu, 2 Mar 2017 14:19:49 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Andy Shevchenko <andy.shevchenko@...il.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Linus Walleij <linus.walleij@...aro.org>, swarren@...dia.com,
        Al Cooper <alcooperx@...il.com>,
        "open list:PIN CONTROL SUBSYSTEM" <linux-gpio@...r.kernel.org>
Subject: Re: [PATCH fixes v3] pinctrl: Really force states during
 suspend/resume

On 03/02/2017 12:54 AM, Andy Shevchenko wrote:
> On Wed, Mar 1, 2017 at 8:32 PM, 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 the actual state change from
>> pinctrl_select_state() and move it pinctrl_commit_state(), while keeping
>> the p->state == state check in pinctrl_select_state() not to change the
>> caller assumptions. pinctrl_force_sleep() and pinctrl_force_default()
>> are updated to bypass the state check by calling pinctrl_commit_state().
>>
>> Fixes: 6e5e959dde0d ("pinctrl: API changes to support multiple states per device")
>> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
> 
> This change is indeed beautiful and clean.
> 
> FWIW:
> Reviewed-by: Andy Shevchenko <andy.shevchenko@...il.com>

Thanks Andy!

So actually, I have been thinking about this some more, and while this
definitively fixes my original problem with pinctrl-single, I just had
to make another driver (sdhci-brcmstb.c) pinctrl aware. And then again,
same thing, it has got just one "default" state, so when we call
pinctrl_select_state() during driver resume, nothing happens.

So, with that in mind, it seems to me like we may actually just want to
remove the p->state == state statement entirely, even though that's an
optimization....

... or, what we could do is, expose a version of pinctrl_force_default
that takes a struct pinctrl reference instead of a struct pinctrl_dev
reference and named differently of course.

Thoughts?

> 
> 
>> ---
>> Changes in v3:
>>
>> - move the state check to pinctrl_select_state
>>
>> Changes in v2:
>>
>> - rename __pinctrl_select_state to pinctrl_commit_state
>>
>>  drivers/pinctrl/core.c | 24 +++++++++++++++++-------
>>  1 file changed, 17 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
>> index fb38e208f32d..735d8f7f9d71 100644
>> --- a/drivers/pinctrl/core.c
>> +++ b/drivers/pinctrl/core.c
>> @@ -992,19 +992,16 @@ 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_commit_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)
>> +static int pinctrl_commit_state(struct pinctrl *p, struct pinctrl_state *state)
>>  {
>>         struct pinctrl_setting *setting, *setting2;
>>         struct pinctrl_state *old_state = p->state;
>>         int ret;
>>
>> -       if (p->state == state)
>> -               return 0;
>> -
>>         if (p->state) {
>>                 /*
>>                  * For each pinmux setting in the old state, forget SW's record
>> @@ -1068,6 +1065,19 @@ 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)
>> +{
>> +       if (p->state == state)
>> +               return 0;
>> +
>> +       return pinctrl_commit_state(p, state);
>> +}
>>  EXPORT_SYMBOL_GPL(pinctrl_select_state);
>>
>>  static void devm_pinctrl_release(struct device *dev, void *res)
>> @@ -1236,7 +1246,7 @@ 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_commit_state(pctldev->p, pctldev->hog_sleep);
>>         return 0;
>>  }
>>  EXPORT_SYMBOL_GPL(pinctrl_force_sleep);
>> @@ -1248,7 +1258,7 @@ 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_commit_state(pctldev->p, pctldev->hog_default);
>>         return 0;
>>  }
>>  EXPORT_SYMBOL_GPL(pinctrl_force_default);
>> --
>> 2.9.3
>>
> 
> 
> 


-- 
Florian