linux-kernel - Re: [PATCH] power: supply: bq256xx: Remove init ichg/vbat with max value

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Message-ID: <20221129152715.4hwtobuv57hrndzu@mercury.elektranox.org>
Date:   Tue, 29 Nov 2022 16:27:15 +0100
From:   Sebastian Reichel <sebastian.reichel@...labora.com>
To:     Hermes Zhang <chenhuiz@...s.com>
Cc:     kernel@...s.com, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] power: supply: bq256xx: Remove init ichg/vbat with max
 value

Hi,

On Tue, Nov 29, 2022 at 05:01:12PM +0800, Hermes Zhang wrote:
> Init the ichg and vbat reg with max value is not good. First the chip
> already has a default value for ichg and vbat (small value). Init these
> two reg with max value will result an unsafe case (e.g. battery is over
> charging in a hot environment) if no user space change them later.
> 
> Signed-off-by: Hermes Zhang <chenhuiz@...s.com>
> ---

It's the driver's task to setup safe initial maximum values.
Pre-kernel values may or may not be safe if you consider things
like kexec. If you get unsafe values programmed, then fix the
values instead.

-- Sebastian

>  drivers/power/supply/bq256xx_charger.c | 10 ----------
>  1 file changed, 10 deletions(-)
> 
> diff --git a/drivers/power/supply/bq256xx_charger.c b/drivers/power/supply/bq256xx_charger.c
> index 01ad84fd147c..d1aa92c10c22 100644
> --- a/drivers/power/supply/bq256xx_charger.c
> +++ b/drivers/power/supply/bq256xx_charger.c
> @@ -1562,21 +1562,11 @@ static int bq256xx_hw_init(struct bq256xx_device *bq)
>  	if (ret)
>  		return ret;
>  
> -	ret = bq->chip_info->bq256xx_set_ichg(bq,
> -				bat_info->constant_charge_current_max_ua);
> -	if (ret)
> -		return ret;
> -
>  	ret = bq->chip_info->bq256xx_set_iprechg(bq,
>  				bat_info->precharge_current_ua);
>  	if (ret)
>  		return ret;
>  
> -	ret = bq->chip_info->bq256xx_set_vbatreg(bq,
> -				bat_info->constant_charge_voltage_max_uv);
> -	if (ret)
> -		return ret;
> -
>  	ret = bq->chip_info->bq256xx_set_iterm(bq,
>  				bat_info->charge_term_current_ua);
>  	if (ret)
> -- 
> 2.30.2
> 

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