linux-kernel - Re: [PATCH] firmware/psci: Move psci_init_system_suspend() to late

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Date: Fri, 23 Feb 2024 14:34:10 +0530
From: Dhruva Gole <d-gole@...com>
To: "Maulik Shah (mkshah)" <quic_mkshah@...cinc.com>
CC: Lorenzo Pieralisi <lpieralisi@...nel.org>,
        Mark Rutland
	<mark.rutland@....com>, <andersson@...nel.org>,
        <ulf.hansson@...aro.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>,
        <linux-pm@...r.kernel.org>, <quic_lsrao@...cinc.com>,
        <stable@...r.kernel.org>
Subject: Re: [PATCH] firmware/psci: Move psci_init_system_suspend() to
 late_initcall()

On Feb 20, 2024 at 11:18:39 +0530, Maulik Shah (mkshah) wrote:
> 
> 
> On 2/19/2024 10:59 PM, Lorenzo Pieralisi wrote:
> > On Mon, Feb 19, 2024 at 03:02:04PM +0530, Maulik Shah wrote:
> > > psci_init_system_suspend() invokes suspend_set_ops() very early during
> > > bootup even before kernel command line for mem_sleep_default is setup.
> > > This leads to kernel command line mem_sleep_default=s2idle not working
> > > as mem_sleep_current gets changed to deep via suspend_set_ops() and never
> > > changes back to s2idle.
> > > 
> > > Move psci_init_system_suspend() to late_initcall() to make sure kernel
> > > command line mem_sleep_default=s2idle sets up s2idle as default suspend
> > > mode.
> > 
> > Why can't we fix it the other way around, namely enforce
> > mem_sleep_current according to the mem_sleep_default command line
> > even if suspend_set_ops() was already called ?
> 
> yes, this may be fixed other way also and i did not implement other way
> since mem_sleep_default_setup() only update mem_sleep_default and to avoid
> this race, it needs to also need to update mem_sleep_current along
> with it. Below change also resolves the issue.
> 
> --- a/kernel/power/suspend.c
> +++ b/kernel/power/suspend.c
> @@ -192,6 +192,7 @@ static int __init mem_sleep_default_setup(char *str)
>                 if (mem_sleep_labels[state] &&
>                     !strcmp(str, mem_sleep_labels[state])) {
>                         mem_sleep_default = state;
> +                       mem_sleep_current = state;
>                         break;
>                 }
> 
> however it may be erasing thin line between mem_sleep_default v/s
> mem_sleep_current as both gets updated while set up of mem_sleep_default.
> 
> if this change looks Ok, i can send v2 with it.

Honestly, I don't see too much of a problem with this, it only makes
sense that we're starting off with a default sleep state which means
that it will be considered as "current" sleep state.

For the issue that you described originally, I think this is a fine
solution.

> 
> > 
> > Just asking, I am not super keen on using initcalls ordering, it
> > looks fragile to me.
> 
> i agree with above.

Same.


-- 
Best regards,
Dhruva Gole <d-gole@...com>