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

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Message-ID: <ZdOP5oAwZvEhNAsn@lpieralisi>
Date: Mon, 19 Feb 2024 18:29:10 +0100
From: Lorenzo Pieralisi <lpieralisi@...nel.org>
To: Maulik Shah <quic_mkshah@...cinc.com>
Cc: 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 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 ?

Just asking, I am not super keen on using initcalls ordering, it
looks fragile to me.

Thanks,
Lorenzo

> Fixes: faf7ec4a92c0 ("drivers: firmware: psci: add system suspend support")
> CC: stable@...r.kernel.org # 5.15+
> Signed-off-by: Maulik Shah <quic_mkshah@...cinc.com>
> ---
>  drivers/firmware/psci/psci.c | 13 ++++++++++---
>  1 file changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/firmware/psci/psci.c b/drivers/firmware/psci/psci.c
> index d9629ff87861..655a2db70a67 100644
> --- a/drivers/firmware/psci/psci.c
> +++ b/drivers/firmware/psci/psci.c
> @@ -523,18 +523,26 @@ static void __init psci_init_system_reset2(void)
>  		psci_system_reset2_supported = true;
>  }
>  
> -static void __init psci_init_system_suspend(void)
> +static int __init psci_init_system_suspend(void)
>  {
>  	int ret;
> +	u32 ver;
>  
>  	if (!IS_ENABLED(CONFIG_SUSPEND))
> -		return;
> +		return 0;
> +
> +	ver = psci_0_2_get_version();
> +	if (PSCI_VERSION_MAJOR(ver) < 1)
> +		return 0;
>  
>  	ret = psci_features(PSCI_FN_NATIVE(1_0, SYSTEM_SUSPEND));
>  
>  	if (ret != PSCI_RET_NOT_SUPPORTED)
>  		suspend_set_ops(&psci_suspend_ops);
> +
> +	return ret;
>  }
> +late_initcall(psci_init_system_suspend)
>  
>  static void __init psci_init_cpu_suspend(void)
>  {
> @@ -651,7 +659,6 @@ static int __init psci_probe(void)
>  	if (PSCI_VERSION_MAJOR(ver) >= 1) {
>  		psci_init_smccc();
>  		psci_init_cpu_suspend();
> -		psci_init_system_suspend();
>  		psci_init_system_reset2();
>  		kvm_init_hyp_services();
>  	}
> 
> ---
> base-commit: d37e1e4c52bc60578969f391fb81f947c3e83118
> change-id: 20240219-suspend_ops_late_init-27fb0b15baee
> 
> Best regards,
> -- 
> Maulik Shah <quic_mkshah@...cinc.com>
>