linux-kernel - Re: [PATCH v5 2/6] ARM: imx6: register pm_power_off handler if "fsl,pmic-stby-poweroff" is set

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Date:   Mon, 19 Jun 2017 14:35:33 +0300
From:   Leonard Crestez <leonard.crestez@....com>
To:     Oleksij Rempel <o.rempel@...gutronix.de>
CC:     Andrew Morton <akpm@...ux-foundation.org>,
        <devicetree@...r.kernel.org>,
        Fabio Estevam <fabio.estevam@....com>, <kernel@...gutronix.de>,
        Liam Girdwood <lgirdwood@...il.com>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-clk@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        Mark Brown <broonie@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        "Michael Turquette" <mturquette@...libre.com>,
        Rob Herring <robh+dt@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        Shawn Guo <shawnguo@...nel.org>,
        Stephen Boyd <sboyd@...eaurora.org>
Subject: Re: [PATCH v5 2/6] ARM: imx6: register pm_power_off handler if
 "fsl,pmic-stby-poweroff" is set

On Mon, 2017-06-19 at 07:02 +0200, Oleksij Rempel wrote:
> One of the Freescale recommended sequences for power off with
> external
> PMIC is the following:
> ...
> 3.  SoC is programming PMIC for power off when standby is asserted.
> 4.  In CCM STOP mode, Standby is asserted, PMIC gates SoC supplies.
> 
> See:
> https://emea01.safelinks.protection.outlook.com/?url=http%3A%2F%2Fwww
> .nxp.com%2Fassets%2Fdocuments%2Fdata%2Fen%2Freference-
> manuals%2FIMX6DQRM.pdf&data=01%7C01%7Cleonard.crestez%40nxp.com%7C32c
> df19d0ab44ed8e24d08d4b6d097f4%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0&
> sdata=CWDpnEGikPGmSTM3dQH8IMxQCVzcIvHL69nu962d8M0%3D&reserved=0
> page 5083
> 
> This patch implements step 4. of this sequence.
> 
> Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
> ---
>  arch/arm/mach-imx/pm-imx6.c | 25 +++++++++++++++++++++++++
>  1 file changed, 25 insertions(+)
> 
> diff --git a/arch/arm/mach-imx/pm-imx6.c b/arch/arm/mach-imx/pm-
> imx6.c
> index e61b1d1027e1..cb76832935f0 100644
> --- a/arch/arm/mach-imx/pm-imx6.c
> +++ b/arch/arm/mach-imx/pm-imx6.c
> @@ -602,6 +602,28 @@ static void __init imx6_pm_common_init(const
> struct imx6_pm_socdata
>  				   IMX6Q_GPR1_GINT);
>  }
>  
> +static void imx6_pm_poweroff(void)
> +{
> +	imx6_set_lpm(STOP_POWER_OFF);
> +	cpu_suspend(0, imx6q_suspend_finish);

It's a bit strange that you're using parts of the suspend code for
this. Perhaps you could just write your bits to CLPCR and then execute
a WFI?

It would also be nice to rename this to something like
imx6_pm_stby_poweroff to make it clear that it's only for a certain
power off path.