linux-kernel - Re: [PATCH v1] mfd: tps65910: Correct power-off programming sequence

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Date:   Fri, 15 May 2020 15:30:11 +0200
From:   Michał Mirosław <mirq-linux@...e.qmqm.pl>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Tony Lindgren <tony@...mide.com>, Lee Jones <lee.jones@...aro.org>,
        Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Zack Pearsall <zpearsall@...oo.com>,
        linux-tegra@...r.kernel.org, linux-omap@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] mfd: tps65910: Correct power-off programming sequence

On Thu, May 14, 2020 at 11:50:21PM +0300, Dmitry Osipenko wrote:
> This patch fixes system shutdown on a devices that use TPS65910 as a
> system's power controller. In accordance to the TPS65910 datasheet, the
> PMIC's state-machine transitions into the OFF state only when DEV_OFF
> bit of DEVCTRL_REG is set. The ON / SLEEP states also should be cleared,
> otherwise PMIC won't get into a proper state on shutdown. Devices like
> Nexus 7 tablet and Ouya game console are now shutting down properly.
> 
> Tested-by: Zack Pearsall <zpearsall@...oo.com>
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>  drivers/mfd/tps65910.c | 12 ++++++++++--
>  1 file changed, 10 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mfd/tps65910.c b/drivers/mfd/tps65910.c
> index 11959021b50a..22116cee411d 100644
> --- a/drivers/mfd/tps65910.c
> +++ b/drivers/mfd/tps65910.c
> @@ -440,8 +440,16 @@ static void tps65910_power_off(void)
>  			DEVCTRL_PWR_OFF_MASK) < 0)
>  		return;
>  
> -	tps65910_reg_clear_bits(tps65910, TPS65910_DEVCTRL,
> -			DEVCTRL_DEV_ON_MASK);
> +	if (tps65910_reg_clear_bits(tps65910, TPS65910_DEVCTRL,
> +			DEVCTRL_DEV_SLP_MASK) < 0)
> +		return;
> +
> +	if (tps65910_reg_clear_bits(tps65910, TPS65910_DEVCTRL,
> +			DEVCTRL_DEV_ON_MASK) < 0)
> +		return;
> +
> +	tps65910_reg_set_bits(tps65910, TPS65910_DEVCTRL,
> +			DEVCTRL_DEV_OFF_MASK);
>  }

Isn't it enough to update the DEVCTRL with just one
tps65910_reg_update_bits()?

Best Regards
Michał Mirosław