Re: [PATCH] power: supply: max17042_battery: Fix SOC threshold calc w/ no current sense

[Henrik Grimler <henrik@grimler.se>]

On Sat, Aug 17, 2024 at 12:51:14PM +0200, Artur Weber wrote:
> Commit 223a3b82834f ("power: supply: max17042_battery: use VFSOC for
> capacity when no rsns") made it so that capacity on systems without
> current sensing would be read from VFSOC instead of RepSOC. However,
> the SOC threshold calculation still read RepSOC to get the SOC
> regardless of the current sensing option state.
> 
> Fix this by applying the same conditional to determine which register
> should be read.
> 
> This also seems to be the intended behavior as per the datasheet - SOC
> alert config value in MiscCFG on setups without current sensing is set
> to a value of 0b11, indicating SOC alerts being generated based on
> VFSOC, instead of 0b00 which indicates SOC alerts being generated based
> on RepSOC.
> 
> This fixes an issue on the Galaxy S3/Midas boards, where the alert
> interrupt would be constantly retriggered, causing high CPU usage
> on idle (around ~12%-15%).
> 
> Fixes: e5f3872d2044 ("max17042: Add support for signalling change in SOC")
> Signed-off-by: Artur Weber <aweber.kernel@gmail.com>

Reviewed-by: Henrik Grimler <henrik@grimler.se>

Can confirm that this fixes high irq CPU usage on exynos4412-i9300 and
exynos4412-i9305, thanks!

Best regards
Henrik Grimler

> ---
> Commit 223a3b82834f ("power: supply: max17042_battery: use VFSOC for
> capacity when no rsns") made it so that capacity on systems without
> current sensing would be read from VFSOC instead of RepSOC. However,
> the SOC threshold calculation still read RepSOC to get the SOC
> regardless of the current sensing option state.
> 
> Fix this by applying the same conditional to determine which register
> should be read.
> 
> This also seems to be the intended behavior as per the datasheet - SOC
> alert config value in MiscCFG on setups without current sensing is set
> to a value of 0b11, indicating SOC alerts being generated based on
> VFSOC, instead of 0b00 which indicates SOC alerts being generated based
> on RepSOC.
> 
> This fixes an issue on the Galaxy S3/Midas boards, where the alert
> interrupt would be constantly retriggered, causing high CPU usage
> on idle (around ~12%-15%).
> ---
>  drivers/power/supply/max17042_battery.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/power/supply/max17042_battery.c b/drivers/power/supply/max17042_battery.c
> index e7d37e422c3f..496c3e1f2ee6 100644
> --- a/drivers/power/supply/max17042_battery.c
> +++ b/drivers/power/supply/max17042_battery.c
> @@ -853,7 +853,10 @@ static void max17042_set_soc_threshold(struct max17042_chip *chip, u16 off)
>  	/* program interrupt thresholds such that we should
>  	 * get interrupt for every 'off' perc change in the soc
>  	 */
> -	regmap_read(map, MAX17042_RepSOC, &soc);
> +	if (chip->pdata->enable_current_sense)
> +		regmap_read(map, MAX17042_RepSOC, &soc);
> +	else
> +		regmap_read(map, MAX17042_VFSOC, &soc);
>  	soc >>= 8;
>  	soc_tr = (soc + off) << 8;
>  	if (off < soc)
> 
> ---
> base-commit: 0c3836482481200ead7b416ca80c68a29cfdaabd
> change-id: 20240817-max17042-soc-threshold-fix-e96f15a622e5
> 
> Best regards,
> -- 
> Artur Weber <aweber.kernel@gmail.com>
>