linux-kernel - Re: [PATCH 1/2] pinctrl: Allow a device to indicate when to force a state

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Date:   Fri, 22 Sep 2017 13:47:04 +0100
From:   Charles Keepax <ckeepax@...nsource.cirrus.com>
To:     Florian Fainelli <f.fainelli@...il.com>
CC:     <linux-kernel@...r.kernel.org>, <linus.walleij@...aro.org>,
        <swarren@...dia.com>, <andy.shevchenko@...il.com>,
        <alcooperx@...il.com>, <linux-gpio@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <robh+dt@...nel.org>,
        <mark.rutland@....com>, <bcm-kernel-feedback-list@...adcom.com>
Subject: Re: [PATCH 1/2] pinctrl: Allow a device to indicate when to force a
 state

On Wed, Sep 20, 2017 at 06:04:20PM -0700, Florian Fainelli wrote:
> It may happen that a device needs to force applying a state, e.g:
> because it only defines one state of pin states (default) but loses
> power/register contents when entering low power modes. Add a
> pinctrl_dev::flags bitmask to help describe future quirks and define
> PINCTRL_FLG_FORCE_STATE as such a settable flag.
> 
> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
> ---
>  drivers/pinctrl/core.c | 15 +++++++++++++++
>  drivers/pinctrl/core.h |  4 ++++
>  2 files changed, 19 insertions(+)
> 
> diff --git a/drivers/pinctrl/core.c b/drivers/pinctrl/core.c
> index 56fbe4c3e800..c450a97de88f 100644
> --- a/drivers/pinctrl/core.c
> +++ b/drivers/pinctrl/core.c
> @@ -1197,11 +1197,26 @@ int pinctrl_select_state(struct pinctrl *p, struct pinctrl_state *state)
>  {
>  	struct pinctrl_setting *setting, *setting2;
>  	struct pinctrl_state *old_state = p->state;
> +	bool force = false;
>  	int ret;
>  
>  	if (p->state == state)
>  		return 0;

I am guessing you probably intended to remove these two lines.

>  
> +	if (p->state) {
> +		list_for_each_entry(setting, &p->state->settings, node) {
> +			if (setting->pctldev->flags & PINCTRL_FLG_FORCE_STATE)
> +				force = true;
> +		}
> +	}
> +
> +	/* Some controllers may want to force this operation when they define
> +	 * only one set of functions and lose power state, e.g: pinctrl-single
> +	 * with its pinctrl-single,low-power-state-loss property.
> +	 */
> +	if (p->state == state && !force)
> +		return 0;
> +

Thanks,
Charles