linux-kernel - Re: [PATCH V5 02/18] pinctrl: tegra: Add suspend and resume support

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Message-ID: <db7ac8e6-bfad-bc60-b46e-d886025872e4@nvidia.com>
Date:   Fri, 12 Jul 2019 22:31:20 -0700
From:   Sowjanya Komatineni <skomatineni@...dia.com>
To:     Dmitry Osipenko <digetx@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>
CC:     "thierry.reding@...il.com" <thierry.reding@...il.com>,
        Jon Hunter <jonathanh@...dia.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Marc Zyngier <marc.zyngier@....com>,
        Stefan Agner <stefan@...er.ch>,
        Mark Rutland <mark.rutland@....com>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        Prashant Gaikwad <pgaikwad@...dia.com>,
        "Stephen Boyd" <sboyd@...nel.org>,
        linux-clk <linux-clk@...r.kernel.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        <jckuo@...dia.com>, "Joseph Lo" <josephl@...dia.com>,
        <talho@...dia.com>, <linux-tegra@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "Mikko Perttunen" <mperttunen@...dia.com>, <spatra@...dia.com>,
        Rob Herring <robh+dt@...nel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@...r.kernel.org>
Subject: Re: [PATCH V5 02/18] pinctrl: tegra: Add suspend and resume support


On 7/4/19 3:40 AM, Dmitry Osipenko wrote:
> 04.07.2019 10:31, Linus Walleij пишет:
>> On Sat, Jun 29, 2019 at 5:58 PM Dmitry Osipenko <digetx@...il.com> wrote:
>>
>>> Oh, also what about GPIO-pinctrl suspend resume ordering .. is it okay that pinctrl
>>> will be resumed after GPIO? Shouldn't a proper pin-muxing be selected at first?
>> Thierry sent some initial patches about this I think. We need to use
>> device links for this to work properly so he adds support for
>> linking the pinctrl and GPIO devices through the ranges.
>>
>> For links between pin control handles and their consumers, see also:
>> 036f394dd77f pinctrl: Enable device link creation for pin control
>> c6045b4e3cad pinctrl: stmfx: enable links creations
>> 489b64d66325 pinctrl: stm32: Add links to consumers
>>
>> I am using STM32 as guinea pig for this, consider adding links also
>> from the Tegra pinctrl. I might simply make these pinctrl consumer
>> to producer links default because I think it makes a lot sense.
> IIUC, currently the plan is to resume pinctrl *after* GPIO for Tegra210 [1]. But this
> contradicts to what was traditionally done for older Tegras where pinctrl was always
> resumed first and apparently it won't work well for the GPIO ranges as well. I think this
> and the other patchsets related to suspend-resume still need some more thought.
>
> [1] https://patchwork.kernel.org/patch/11012077/

Park bit was introduced from Tegra210 onwards and during suspend/resume, 
requirement of gpio restore prior to pinctrl restore is not required for 
prior Tegra210.

Also currently pinctrl suspend/resume implementation for prior Tegra210 
is not yet upstreamed but having gpio restore prior to pinmux during 
suspend/resume should not cause any issue for prior tegra's as well as 
gpio resume restores pins back to same gpio config as they were during 
suspend entry.