Re: [RFC PATCH] power: supply: fix circular dependency with cooling device

[Luca Weiss <luca@z3ntu.xyz>]

On Sonntag, 1. Jänner 2023 18:43:40 CET Caleb Connolly wrote:
> A recent change in thermal/core means it now calls the cooling device
> ->get_max_state() callback during __thermal_cooling_device_register().
> This creates a circular dependency as it attempts to fetch a power
> supply property before the psy is initialised. Move this call later to
> break the dependency.
> 
> Fixes: c408b3d1d9bb ("thermal: Validate new state in cur_state_store()")
> Signed-off-by: Caleb Connolly <caleb.connolly@linaro.org>

Fixes USB on qcom-apq8026-lg-lenok (with smbb driver)

Tested-by: Luca Weiss <luca@z3ntu.xyz>

Regards
Luca

> ---
>  drivers/power/supply/power_supply_core.c | 18 ++++++++++++------
>  1 file changed, 12 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/power/supply/power_supply_core.c
> b/drivers/power/supply/power_supply_core.c index 7c790c41e2fe..c921111ff26a
> 100644
> --- a/drivers/power/supply/power_supply_core.c
> +++ b/drivers/power/supply/power_supply_core.c
> @@ -1354,10 +1354,6 @@ __power_supply_register(struct device *parent,
>  	if (rc)
>  		goto register_thermal_failed;
> 
> -	rc = psy_register_cooler(psy);
> -	if (rc)
> -		goto register_cooler_failed;
> -
>  	rc = power_supply_create_triggers(psy);
>  	if (rc)
>  		goto create_triggers_failed;
> @@ -1378,17 +1374,27 @@ __power_supply_register(struct device *parent,
>  	atomic_inc(&psy->use_cnt);
>  	psy->initialized = true;
> 
> +	/* This has to be done after updating use_cnt and initialized
> +	 * otherwise when __thermal_cooling_device_register calls back
> +	 * to ->get_max_state() the psy core will return -EAGAIN..
> +	 */
> +	rc = psy_register_cooler(psy);
> +	if (rc)
> +		goto register_cooler_failed;
> +
>  	queue_delayed_work(system_power_efficient_wq,
>  			   &psy->deferred_register_work,
>  			   POWER_SUPPLY_DEFERRED_REGISTER_TIME);
> 
>  	return psy;
> 
> +register_cooler_failed:
> +	power_supply_remove_hwmon_sysfs(psy);
> +	psy->initialized = false;
> +	atomic_dec(&psy->use_cnt);
>  add_hwmon_sysfs_failed:
>  	power_supply_remove_triggers(psy);
>  create_triggers_failed:
> -	psy_unregister_cooler(psy);
> -register_cooler_failed:
>  	psy_unregister_thermal(psy);
>  register_thermal_failed:
>  wakeup_init_failed: