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Date:   Mon, 3 Jun 2019 13:45:16 +0100
From:   Lee Jones <lee.jones@linaro.org>
To:     Stefan Mavrodiev <stefan@olimex.com>
Cc:     Heiko Stuebner <heiko@sntech.de>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/2] mfd: rk808: Check pm_power_off pointer
Message-ID: <20190603124516.GP4797@dell>
References: <20190521062449.29410-1-stefan@olimex.com>
 <20190521062449.29410-2-stefan@olimex.com>
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On Tue, 21 May 2019, Stefan Mavrodiev wrote:

> The function pointer pm_power_off may point to function from other
> module (PSCI for example). If rk808 is removed, pm_power_off is
> overwritten to NULL and the system cannot be powered off.
> 
> This patch checks if pm_power_off points to a module function.
> 
> Signed-off-by: Stefan Mavrodiev <stefan@olimex.com>
> ---
> Changes in v2:
>  - Initial release actually
> 
>  drivers/mfd/rk808.c       | 13 +++++++------
>  include/linux/mfd/rk808.h |  1 +
>  2 files changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/mfd/rk808.c b/drivers/mfd/rk808.c
> index 94377782d208..c0b179792bbf 100644
> --- a/drivers/mfd/rk808.c
> +++ b/drivers/mfd/rk808.c
> @@ -438,7 +438,6 @@ static int rk808_probe(struct i2c_client *client,
>  	struct rk808 *rk808;
>  	const struct rk808_reg_data *pre_init_reg;
>  	const struct mfd_cell *cells;
> -	void (*pm_pwroff_fn)(void);
>  	int nr_pre_init_regs;
>  	int nr_cells;
>  	int pm_off = 0, msb, lsb;
> @@ -475,7 +474,7 @@ static int rk808_probe(struct i2c_client *client,
>  		nr_pre_init_regs = ARRAY_SIZE(rk805_pre_init_reg);
>  		cells = rk805s;
>  		nr_cells = ARRAY_SIZE(rk805s);
> -		pm_pwroff_fn = rk805_device_shutdown;
> +		rk808->pm_pwroff_fn = rk805_device_shutdown;
>  		break;
>  	case RK808_ID:
>  		rk808->regmap_cfg = &rk808_regmap_config;
> @@ -484,7 +483,7 @@ static int rk808_probe(struct i2c_client *client,
>  		nr_pre_init_regs = ARRAY_SIZE(rk808_pre_init_reg);
>  		cells = rk808s;
>  		nr_cells = ARRAY_SIZE(rk808s);
> -		pm_pwroff_fn = rk808_device_shutdown;
> +		rk808->pm_pwroff_fn = rk808_device_shutdown;
>  		break;
>  	case RK818_ID:
>  		rk808->regmap_cfg = &rk818_regmap_config;
> @@ -493,7 +492,7 @@ static int rk808_probe(struct i2c_client *client,
>  		nr_pre_init_regs = ARRAY_SIZE(rk818_pre_init_reg);
>  		cells = rk818s;
>  		nr_cells = ARRAY_SIZE(rk818s);
> -		pm_pwroff_fn = rk818_device_shutdown;
> +		rk808->pm_pwroff_fn = rk818_device_shutdown;
>  		break;
>  	default:
>  		dev_err(&client->dev, "Unsupported RK8XX ID %lu\n",
> @@ -548,7 +547,7 @@ static int rk808_probe(struct i2c_client *client,
>  				"rockchip,system-power-controller");
>  	if (pm_off && !pm_power_off) {
>  		rk808_i2c_client = client;
> -		pm_power_off = pm_pwroff_fn;
> +		pm_power_off = rk808->pm_pwroff_fn;
>  	}
>  
>  	return 0;
> @@ -563,7 +562,9 @@ static int rk808_remove(struct i2c_client *client)
>  	struct rk808 *rk808 = i2c_get_clientdata(client);
>  
>  	regmap_del_irq_chip(client->irq, rk808->irq_data);
> -	pm_power_off = NULL;
> +
> +	if (rk808->pm_pwroff_fn && pm_power_off == rk808->pm_pwroff_fn)
> +		pm_power_off = NULL;

The idea seems sound, but I think you should comment this statement.

-- 
Lee Jones [李琼斯]
Linaro Services Technical Lead
Linaro.org │ Open source software for ARM SoCs
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