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

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Date: Tue, 20 Feb 2024 11:18:39 +0530
From: "Maulik Shah (mkshah)" <quic_mkshah@...cinc.com>
To: Lorenzo Pieralisi <lpieralisi@...nel.org>
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 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.

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

i agree with above.

Thanks,
Maulik