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:   Tue, 20 Jun 2017 06:55:24 +0200
From:   Oleksij Rempel <ore@...gutronix.de>
To:     Leonard Crestez <leonard.crestez@....com>,
        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

Hi Leonard,

On 19.06.2017 13:35, Leonard Crestez wrote:
> 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?

Well, every thing in this patch set, yell about using standby/suspend 
path in HW for power off. Even iMX code use STOP_POWER_OFF for 
configuring this regs. How can it be more strange? :) Should i really 
duplicate code to hide this?

> 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.

ok.