linux-kernel - Re: [PATCH 2/2] pinctrl: single: Allow indicating loss of pin states during low-power

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Message-ID: <CACRpkdbmrEottfArW-Hnv63M1k4zASfMg7W+SUNY6D1N2nxOVA@mail.gmail.com>
Date:   Fri, 22 Sep 2017 15:03:45 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Florian Fainelli <f.fainelli@...il.com>,
        ext Tony Lindgren <tony@...mide.com>
Cc:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Stephen Warren <swarren@...dia.com>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Al Cooper <alcooperx@...il.com>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        bcm-kernel-feedback-list <bcm-kernel-feedback-list@...adcom.com>
Subject: Re: [PATCH 2/2] pinctrl: single: Allow indicating loss of pin states
 during low-power

On Thu, Sep 21, 2017 at 3:04 AM, Florian Fainelli <f.fainelli@...il.com> wrote:

> Some platforms (e.g: Broadcom STB: BMIPS_GENERIC/ARCH_BRCMSTB) will lose
> their register contents when entering their lower power state. In such a
> case, the pinctrl-single driver that is used will not be able to restore
> the power states without telling the core about it and having
> pinctrl_select_state() check for that.
>
> This patch adds a new optional boolean property that Device Tree can
> define in order to obtain exactly that and having the core pinctrl code
> take that into account.
>
> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>

If we use this per-controller approach rather than the per-state approach
I discuss in reply to patch 1/2, we should probably make it a generic
property for pin controllers and not just a pinctrl-single business.

So patch pinctrl-bindings.txt and put the code somewhere in
core.

But that is more of a detail, first we need to figure out how to
handle this business in general.

Yours,
Linus Walleij