linux-kernel - Re: [RESEND PATCH v3] mfd: tps65219: Add support for soft shutdown via sys-off API

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Message-ID: <cf051fe221d0d455b3d45c5610e1e31fea560c47.camel@siemens.com>
Date: Fri, 15 Nov 2024 08:15:56 +0000
From: "Sverdlin, Alexander" <alexander.sverdlin@...mens.com>
To: "lee@...nel.org" <lee@...nel.org>, "tony@...mide.com" <tony@...mide.com>,
	"jneanne@...libre.com" <jneanne@...libre.com>
CC: "nm@...com" <nm@...com>, "msp@...libre.com" <msp@...libre.com>,
	"afd@...com" <afd@...com>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, "linux-omap@...r.kernel.org"
	<linux-omap@...r.kernel.org>, "khilman@...libre.com" <khilman@...libre.com>
Subject: Re: [RESEND PATCH v3] mfd: tps65219: Add support for soft shutdown
 via sys-off API

Hi Jerome,

On Thu, 2023-06-08 at 09:19 +0200, Jerome Neanne wrote:
> Use new API for power-off mode support:
> Link: https://lwn.net/Articles/894511/
> Link: https://lore.kernel.org/all/7hfseqa7l0.fsf@baylibre.com/
> 
> sys-off API allows support of shutdown handler and restart handler.
> 
> Shutdown was not supported before that enhancement.
> This is required for platform that are not using PSCI.
> 
> Test:
> - restart:
>   # reboot
>   Default is cold reset:
>   # cat /sys/kernel/reboot/mode
>   Switch boot mode to warm reset:
>   # echo warm > /sys/kernel/reboot/mode
> - power-off:
>   # halt
> 
> Tested on AM62-LP-SK board.
> 
> Signed-off-by: Jerome Neanne <jneanne@...libre.com>
> Suggested-by: Andrew Davis <afd@...com>
> Reviewed-by: Andrew Davis <afd@...com>
> ---
> 
> Notes:
>     Change-log v3 to v2
>     v2: Link: https://lore.kernel.org/lkml/20230511122100.2225417-1-jneanne@baylibre.com/
>     Lee Jones Review:
>     nits: rm not needed line wraps and restore a cr deleted not related with the patch.
>     
>     Change-log v2 to v1
>     v1: Link: https://lore.kernel.org/all/20230203140150.13071-1-jneanne@baylibre.com/
>     Andrew Davis Review:
>     - Use new helpers devm_register_restart_handler and devm_register_power_off_handler
>     Vignesh Raghavendra:
>     - Fix typo on board name in commit message
> 
>  drivers/mfd/tps65219.c | 38 ++++++++++++++++++++++++++++----------
>  1 file changed, 28 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/mfd/tps65219.c b/drivers/mfd/tps65219.c
> index 0e402fda206b..3d9164491e20 100644
> --- a/drivers/mfd/tps65219.c
> +++ b/drivers/mfd/tps65219.c
> @@ -25,13 +25,21 @@ static int tps65219_cold_reset(struct tps65219 *tps)
>  				  TPS65219_MFP_COLD_RESET_I2C_CTRL_MASK);
>  }
>  
> -static int tps65219_restart(struct notifier_block *this,
> -			    unsigned long reboot_mode, void *cmd)
> +static int tps65219_soft_shutdown(struct tps65219 *tps)
>  {
> -	struct tps65219 *tps;
> +	return regmap_update_bits(tps->regmap, TPS65219_REG_MFP_CTRL,
> +				  TPS65219_MFP_I2C_OFF_REQ_MASK,
> +				  TPS65219_MFP_I2C_OFF_REQ_MASK);

I suppose this is I2C access and is therefore a [potentially] sleeping call?
Could this be an issue, see below...

> +}
>  
> -	tps = container_of(this, struct tps65219, nb);
> +static int tps65219_power_off_handler(struct sys_off_data *data)
> +{
> +	tps65219_soft_shutdown(data->cb_data);
> +	return NOTIFY_DONE;
> +}
>  
> +static int tps65219_restart(struct tps65219 *tps, unsigned long reboot_mode)
> +{
>  	if (reboot_mode == REBOOT_WARM)
>  		tps65219_warm_reset(tps);
>  	else
> @@ -40,10 +48,11 @@ static int tps65219_restart(struct notifier_block *this,
>  	return NOTIFY_DONE;
>  }
>  
> -static struct notifier_block pmic_rst_restart_nb = {
> -	.notifier_call = tps65219_restart,
> -	.priority = 200,
> -};
> +static int tps65219_restart_handler(struct sys_off_data *data)
> +{
> +	tps65219_restart(data->cb_data, data->mode);
> +	return NOTIFY_DONE;
> +}
>  
>  static const struct resource tps65219_pwrbutton_resources[] = {
>  	DEFINE_RES_IRQ_NAMED(TPS65219_INT_PB_FALLING_EDGE_DETECT, "falling"),
> @@ -269,13 +278,22 @@ static int tps65219_probe(struct i2c_client *client)
>  		}
>  	}
>  
> -	tps->nb = pmic_rst_restart_nb;
> -	ret = register_restart_handler(&tps->nb);
> +	ret = devm_register_restart_handler(tps->dev,
> +					    tps65219_restart_handler,
> +					    tps);
> +
>  	if (ret) {
>  		dev_err(tps->dev, "cannot register restart handler, %d\n", ret);
>  		return ret;
>  	}
>  
> +	ret = devm_register_power_off_handler(tps->dev,
> +					      tps65219_power_off_handler,
> +					      tps);

... while this translates to
        return devm_register_sys_off_handler(dev,
                                             SYS_OFF_MODE_POWER_OFF,
... might this be an issue?

enum sys_off_mode {

[]
        /**
         * @SYS_OFF_MODE_POWER_OFF:
         *
         * Handlers power-off system. Handlers are disallowed to sleep.
         */
        SYS_OFF_MODE_POWER_OFF,


> +	if (ret) {
> +		dev_err(tps->dev, "failed to register power-off handler: %d\n", ret);
> +		return ret;
> +	}
>  	return 0;
>  }

-- 
Alexander Sverdlin
Siemens AG
www.siemens.com