linux-kernel - Re: [PATCH] power: supply: qcom_battmgr: return EAGAIN when firmware service is not up

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Message-ID: <ZpZqxEof85jo-1K3@linaro.org>
Date: Tue, 16 Jul 2024 14:42:44 +0200
From: Stephan Gerhold <stephan.gerhold@...aro.org>
To: Neil Armstrong <neil.armstrong@...aro.org>
Cc: Sebastian Reichel <sre@...nel.org>,
	Bjorn Andersson <andersson@...nel.org>,
	Sebastian Reichel <sebastian.reichel@...labora.com>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	linux-arm-msm@...r.kernel.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	Johan Hovold <johan@...nel.org>, Abel Vesa <abel.vesa@...aro.org>
Subject: Re: [PATCH] power: supply: qcom_battmgr: return EAGAIN when firmware
 service is not up

On Mon, Jul 15, 2024 at 02:57:06PM +0200, Neil Armstrong wrote:
> The driver returns -ENODEV when the firmware battmrg service hasn't
> started yet, while per-se -ENODEV is fine, we usually use -EAGAIN to
> tell the user to retry again later. And the power supply core uses
> -EGAIN when the device isn't initialized, let's use the same return.
> 
> This notably causes an infinite spam of:
> thermal thermal_zoneXX: failed to read out thermal zone (-19)
> because the thermal core doesn't understand -ENODEV, but only
> considers -EAGAIN as a non-fatal error.
> 
> While it didn't appear until now, commit [1] fixes thermal core
> and no more ignores thermal zones returning an error at first
> temperature update.
> 
> [1] 5725f40698b9 ("thermal: core: Call monitor_thermal_zone() if zone temperature is invalid")
> 
> Link: https://lore.kernel.org/all/2ed4c630-204a-4f80-a37f-f2ca838eb455@linaro.org/
> Cc: stable@...r.kernel.org
> Fixes: 29e8142b5623 ("power: supply: Introduce Qualcomm PMIC GLINK power supply")
> Signed-off-by: Neil Armstrong <neil.armstrong@...aro.org>

The "failed to read out thermal zone (-19)" error happens on 6.10 on the
Qualcomm X1E80100 CRD too. This patch fixes it. Thanks for looking into
this! FWIW:

Tested-by: Stephan Gerhold <stephan.gerhold@...aro.org>
Reviewed-by: Stephan Gerhold <stephan.gerhold@...aro.org>

> ---
>  drivers/power/supply/qcom_battmgr.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/power/supply/qcom_battmgr.c b/drivers/power/supply/qcom_battmgr.c
> index 46f36dcb185c..bde874b5e0e7 100644
> --- a/drivers/power/supply/qcom_battmgr.c
> +++ b/drivers/power/supply/qcom_battmgr.c
> @@ -486,7 +486,7 @@ static int qcom_battmgr_bat_get_property(struct power_supply *psy,
>  	int ret;
>  
>  	if (!battmgr->service_up)
> -		return -ENODEV;
> +		return -EAGAIN;
>  
>  	if (battmgr->variant == QCOM_BATTMGR_SC8280XP)
>  		ret = qcom_battmgr_bat_sc8280xp_update(battmgr, psp);
> @@ -683,7 +683,7 @@ static int qcom_battmgr_ac_get_property(struct power_supply *psy,
>  	int ret;
>  
>  	if (!battmgr->service_up)
> -		return -ENODEV;
> +		return -EAGAIN;
>  
>  	ret = qcom_battmgr_bat_sc8280xp_update(battmgr, psp);
>  	if (ret)
> @@ -748,7 +748,7 @@ static int qcom_battmgr_usb_get_property(struct power_supply *psy,
>  	int ret;
>  
>  	if (!battmgr->service_up)
> -		return -ENODEV;
> +		return -EAGAIN;
>  
>  	if (battmgr->variant == QCOM_BATTMGR_SC8280XP)
>  		ret = qcom_battmgr_bat_sc8280xp_update(battmgr, psp);
> @@ -867,7 +867,7 @@ static int qcom_battmgr_wls_get_property(struct power_supply *psy,
>  	int ret;
>  
>  	if (!battmgr->service_up)
> -		return -ENODEV;
> +		return -EAGAIN;
>  
>  	if (battmgr->variant == QCOM_BATTMGR_SC8280XP)
>  		ret = qcom_battmgr_bat_sc8280xp_update(battmgr, psp);
> 
> ---
> base-commit: 91e3b24eb7d297d9d99030800ed96944b8652eaf
> change-id: 20240715-topic-sm8x50-upstream-fix-battmgr-temp-tz-warn-c5a2f956d28d
> 
> Best regards,
> -- 
> Neil Armstrong <neil.armstrong@...aro.org>
>