linux-kernel - Re: [PATCH] power: supply: use ktime

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Message-ID: <d6729dd0-112f-49a6-a08a-d08120588feb@kernel.org>
Date: Wed, 15 Oct 2025 12:04:35 +0200
From: Hans de Goede <hansg@...nel.org>
To: Michal Kubecek <mkubecek@...e.cz>, Sebastian Reichel <sre@...nel.org>,
 linux-pm@...r.kernel.org
Cc: Linus Walleij <linus.walleij@...aro.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] power: supply: use ktime_divns() to avoid 64-bit division

Hi Michal,

On 15-Oct-25 9:56 AM, Michal Kubecek wrote:
> The build of intel_dc_ti_battery module on i386 (32-bit) fails with
> 
> ERROR: modpost: "__udivdi3" [drivers/power/supply/intel_dc_ti_battery.ko]
> 
> This is caused by 64-bit division of ktime values by NSEC_PER_USEC. Use
> ktime_divns() helper which handles the division correctly on 32-bit
> architectures.
> 
> Fixes: 8c5795fe5527 ("power: supply: Add new Intel Dollar Cove TI battery driver")
> Signed-off-by: Michal Kubecek <mkubecek@...e.cz>

Thanks, patch looks good to me:

Reviewed-by: Hans de Goede <hansg@...nel.org>

Regards,

Hans



> ---
>  drivers/power/supply/intel_dc_ti_battery.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/power/supply/intel_dc_ti_battery.c b/drivers/power/supply/intel_dc_ti_battery.c
> index 56b0c92e9d28..c26209ef9577 100644
> --- a/drivers/power/supply/intel_dc_ti_battery.c
> +++ b/drivers/power/supply/intel_dc_ti_battery.c
> @@ -141,7 +141,7 @@ static int dc_ti_battery_get_voltage_and_current_now(struct power_supply *psy, i
>  	if (ret)
>  		goto out_err;
>  
> -	cnt_start_usec = ktime_get_ns() / NSEC_PER_USEC;
> +	cnt_start_usec = ktime_divns(ktime_get_ns(), NSEC_PER_USEC);
>  
>  	/* Read Vbat, convert IIO mV to power-supply ųV */
>  	ret = iio_read_channel_processed_scale(chip->vbat_channel, volt, 1000);
> @@ -149,7 +149,7 @@ static int dc_ti_battery_get_voltage_and_current_now(struct power_supply *psy, i
>  		goto out_err;
>  
>  	/* Sleep at least 3 sample-times + slack to get 3+ CC samples */
> -	now_usec = ktime_get_ns() / NSEC_PER_USEC;
> +	now_usec = ktime_divns(ktime_get_ns(), NSEC_PER_USEC);
>  	sleep_usec = 3 * SMPL_INTVL_US + SLEEP_SLACK_US - (now_usec - cnt_start_usec);
>  	if (sleep_usec > 0 && sleep_usec < 1000000)
>  		usleep_range(sleep_usec, sleep_usec + SLEEP_SLACK_US);