linux-kernel - RE: [PATCH V2] gpio: mxc: add power management support

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Message-ID: <AM3PR04MB13159925074BB583DD83B54DF5530@AM3PR04MB1315.eurprd04.prod.outlook.com>
Date:   Wed, 18 Jul 2018 00:54:36 +0000
From:   Anson Huang <anson.huang@....com>
To:     Fabio Estevam <festevam@...il.com>
CC:     Linus Walleij <linus.walleij@...aro.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        dl-linux-imx <linux-imx@....com>
Subject: RE: [PATCH V2] gpio: mxc: add power management support

Hi, Fabio

Anson Huang
Best Regards!


> -----Original Message-----
> From: Fabio Estevam [mailto:festevam@...il.com]
> Sent: Tuesday, July 17, 2018 9:52 PM
> To: Anson Huang <anson.huang@....com>
> Cc: Linus Walleij <linus.walleij@...aro.org>; open list:GPIO SUBSYSTEM
> <linux-gpio@...r.kernel.org>; linux-kernel <linux-kernel@...r.kernel.org>;
> dl-linux-imx <linux-imx@....com>
> Subject: Re: [PATCH V2] gpio: mxc: add power management support
> 
> Hi Anson,
> 
> [Next time please put the i.mx maintainers on Cc]
> 
> On Mon, Jul 16, 2018 at 3:06 AM, Anson Huang <Anson.Huang@....com>
> wrote:
> > GPIO registers could lose context on i.MX7D, when enter LPSR mode, the
> > whole SoC will be powered off except LPSR domain, GPIO banks will lose
> > context in this case, need to restore the context after resume from
> > LPSR mode.
> >
> > This patch adds GPIO save/restore for those necessary registers, and
> > put the save/restore operations in noirq suspend/resume phase, since
> > GPIO is fundamental module which could be used by other peripherals'
> > resume phase.
> >
> > Signed-off-by: Anson Huang <Anson.Huang@....com>
> 
> >  static struct mxc_gpio_hwdata imx1_imx21_gpio_hwdata = { @@ -434,6
> > +445,9 @@ static int mxc_gpio_probe(struct platform_device *pdev)
> >                 return err;
> >         }
> >
> > +       if (of_machine_is_compatible("fsl,imx7d"))
> > +               port->support_power_off = true;
> 
> This does not scale well as we need to support mx8 soon.
> 
> Like I replied in my last message the best solution here is to add a
> "fsl,imx7d-gpio" compatible entry in this driver.
> 
> Then you can set a flag in the "fsl,imx7d-gpio" case to handle the 'power_off'
> feature.
> 
> With this method there will be no need to touch this driver again for adding
> mx8 support.

Thanks for detail suggestion, I will sent a V3 patch accordingly.

Anson.