linux-kernel - Re: [RESEND 1/2] power_supply: Register cooling device outside of probe

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Message-ID: <20230228002345.625uaporcmcf7kfx@mercury.elektranox.org>
Date:   Tue, 28 Feb 2023 01:23:45 +0100
From:   Sebastian Reichel <sebastian.reichel@...labora.com>
To:     Subbaraman Narayanamurthy <quic_subbaram@...cinc.com>
Cc:     Manaf Meethalavalappu Pallikunhi <quic_manafm@...cinc.com>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        gregkh@...gle.com
Subject: Re: [RESEND 1/2] power_supply: Register cooling device outside of
 probe

Hi,

On Mon, Feb 27, 2023 at 01:46:52PM -0800, Subbaraman Narayanamurthy wrote:
> On 6/9/22 3:12 PM, Sebastian Reichel wrote:
> > Hi,
> >
> > On Wed, Jun 01, 2022 at 12:00:53AM +0530, Manaf Meethalavalappu Pallikunhi wrote:
> >> Registering the cooling device from the probe can result in the
> >> execution of get_property() function before it gets initialized.
> >>
> >> To avoid this, register the cooling device from a workqueue
> >> instead of registering in the probe.
> >>
> >> Signed-off-by: Manaf Meethalavalappu Pallikunhi <quic_manafm@...cinc.com>
> >> ---
> > This removes error handling from the psy_register_cooler() call, so
> > it introduces a new potential problem. If power_supply_get_property()
> > is called to early -EAGAIN is returned. So can you elaborate the problem
> > that you are seeing with the current code?
> >
> > -- Sebastian
> 
> When the device boots up with all the vendor modules getting loaded,           
> here is what we're seeing when booting up with 6.1.11 recently. First          
> log is printed with adding a pr_err() in __power_supply_register().                 
>                                                                                
> [    7.008938][  T682] power_supply battery: psy_register_cooler failed, rc=-11
> [    7.030941][  T682] qti_battery_charger: probe of qcom,battery_charger failed with error -11
>                                                                                
> Here, our downstream qti_battery_charger driver exposes the following          
> power supply properties POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT and             
> POWER_SUPPLY_PROP_CHARGE_CONTROL_LIMIT_MAX under a power supply device.        
>                                                                                
> This is happening because of the following call sequence,                      
>                                                                                
> battery_chg_probe() ->                                                         
>   power_supply_register() ->                                                   
>     psy_register_cooler() ->                                                   
>       thermal_cooling_device_register() ->                                     
>         cdev->ops->get_max_state() ->                                          
>           ps_get_max_charge_cntl_limit() ->                                    
>             power_supply_get_property()                                        
>                                                                                
> ends up calling power_supply_get_property() to read CHARGE_CONTROL_LIMIT       
> property.                                                                      
>                                                                                
> However, it returns -EAGAIN because psy->initialized is set to true            
> later after psy_register_cooler() succeeds. So, this ends up in a              
> driver probe failure forever.

This should be solved in 6.3:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/drivers/power/supply/power_supply_core.c?id=c85c191694cb1cf290b11059b3d2de8a2732ffd0

-- Sebastian

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