linux-kernel - Re: [PATCH v2 0/2] pinctrl: Allow indicating loss of state across suspend/resume

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Message-ID: <76a2b3a9-282e-c3d0-a93b-b75a511806c6@gmail.com>
Date:   Fri, 3 Nov 2017 10:03:22 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Charles Keepax <ckeepax@...nsource.cirrus.com>
Cc:     linux-gpio@...r.kernel.org,
        Linus Walleij <linus.walleij@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>, tony@...mide.com,
        ckeepax@...nsource.wolfsonmicro.com, swarren@...dia.com,
        andy.shevchenko@...il.com, alcooperx@...il.com,
        bcm-kernel-feedback-list@...adcom.com
Subject: Re: [PATCH v2 0/2] pinctrl: Allow indicating loss of state across
 suspend/resume

On 11/03/2017 03:37 AM, Charles Keepax wrote:
> On Thu, Nov 02, 2017 at 04:15:49PM -0700, Florian Fainelli wrote:
>> Hello Linus,
>>
>> It's me again, so I have been thinking about the problem originally
>> reported in: [PATCH fixes v3] pinctrl: Really force states during suspend/resume
>>
>> and other similar patches a while ago, and this new version allows a platform
>> using pinctrl-single to specify whether its pins are going to lose their state
>> during a system deep sleep.
>>
>> Note that this is still checked at the pinctrl_select_state() because consumers
>> of the pinctrl API might be calling this from their suspend/resume functions
>> and should not have to know whether the provider does lose its pin states.
>>
> 
> Still feels to me like it should be the providers job to the
> restore the state rather than expecting the consumer to
> re-request any state it had. But lets wait and see what Linus
> thinks.

The mechanism is generic, but the property needs to be placed at the
pinctrl provider level anyways.

> 
> Also not sure if you have seen this chain, but probably worth a
> look:
> 
> https://www.spinics.net/lists/devicetree/msg200649.html
> 
> It is adding support to the GPIO code for controllers that can
> have options to retain state across reset, not the same but
> probably at least slightly related to this series.

Let me take a closer look and see how much appears applicable.

> 
> Thanks,
> Charles
> 


-- 
Florian