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I just purchased this laptop used and installed Fedora 42 on it.

It’s a Dell Latitude 5420 with an i5-1145G7 processor.

The laptop does not support S3 sleep, only s2idle. It successfully enters and resumes sleep when the lid is closed, but the battery drains rapidly.

I have not done any proper benchmarks but I was at around ~60% battery life last night, and when I opened it this afternoon it was completely dead.

After running the S0ix self test tool, I got the following output:

...
Your system supports S0ix substates, but did not achieve the shallowest s0i2.0
    
Here is the S0ix substates status: 
Substate   Residency      
S0i2.0     0              
S0i3.0     0     
...
Below are the deeper S0ix substate required IPs did not show YES:
    pmc0:            USB2PLL_OFF_STS    Required               
    pmc0:            OPIOPLL_OFF_STS    Required               
    pmc0:                CSME_PG_STS    Required               
    pmc0:                xHCI_PG_STS    Required               
    pmc0:                 GBE_PG_STS    Required               
    pmc0:               xHCI0_D3_STS    Required               
    pmc0:          CPU_C10_REQ_STS_0    Required               
    pmc0:    MPHY_Core_DL_REQ_STS_16    Required

Full output here. Unfortunately I have no idea what this means.

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  • Is it correct that you’re running Fedora 42? Commented Jun 10, 2025 at 9:58
  • 1
    yeah, batteries unless really badly worn don't drain that fast. This sounds like some device in your laptop doesn't shut down alongside with your CPU – either because the firmware doesn't inform it correctly that it should, or because Linux doesn't do it, depending on the type of device. First step would probably ruling out that updating the firmware to the latest version fixes this; luckily easy on Linux: sudo fwupdmgr refresh; and if that yields anything with available updates: sudo fwupdmgr update. Commented Jun 10, 2025 at 10:04

1 Answer 1

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Possible Causes

  • Your OS does not switch or support to the mode

  • Outdated or buggy BIOS/firmware

  • Kernel or driver issues preventing proper power management

  • USB/Thunderbolt peripherals blocking sleep

  • Intel Management Engine (CSME) not entering low-power states

This could also be related to the fact that the Dell Latitude 5420 cannot enter deep S0ix sleep states, particularly S0i2.0 and S0i3.0, which leads to significant battery drain in s2idle (suspend) mode.

In the context of Linux power management, s2idle (Suspend-to-Idle) and S0i3.0 (or similar S0ix variations) are both low-power sleep states, but they differ in how much power is saved and what the system state is during sleep. s2idle is a software-based sleep state that puts the system into a low-power idle state, while S0i3.0 is a hardware-based state that allows the system to enter a low-power idle state with minimal power consumption.

Sleep states are global low-power states of the entire system in which user space code cannot be executed and the overall system activity is significantly reduced.

I reached to Dell support and they told me that they don't support S3 simply because Windows 10 may have BSOD after wake. They don't care about other OS and they don't give customers a choice.

2nd level's story is that my Latitude model does not offer a Wake-On-LAN option. They want a photo of the BIOS page showing the option before they'll proceed. This computer is just over a month old. Support doesn't know the features being offered on their own hardware, but I'm supposed to trust them to fix it.

yes. i have tried this in the past before reinstalling windows. S3 sleep was still not enabled. In Latitudes, S3 sleep is disabled at the BIOS level. May be that was the reason.

s2idle is a software-based sleep state that offers a good balance of power saving and resume latency.

S0i3.0 (S0ix) is a hardware-based sleep state that can offer higher energy efficiency, but may not be supported on all systems.

The choice between s2idle and S0i3.0 depends on the specific hardware capabilities, the desired power saving level, and the need for low-latency resume

Does my laptop use S3 or S0ix? And what is s2idle?

Battery condition

The Dell Latitude 5420 was released in 2021.

Normally, it takes about 1–2 years before the battery noticeably weakens and a significant loss in capacity occurs.

If the battery is constantly charged to 100% or exposed to extreme temperatures, wear and tear will happen faster.

For long-term use on AC power, the battery should be removed if possible.

If the capacity drops below 60%, I would replace the battery with a new one.

However, sometimes the battery behaves differently than expected, even if the capacity is above 60%, some drain faster than others with the same specs.

It also depends on your operating system setup and which programs you’re running.

You can check the battery condition with:

All values from BAT:

upower -i $(upower -e | grep BAT)

Other values for BAT, without commas and percentage values:

cat /sys/class/power_supply/BAT0/uevent

The 3 most important values for the condition:

upower -i $(upower -e | grep BAT) | grep -E 'energy-full|capacity'

The three values indicate the current condition and remaining capacity of the battery:

energy-full shows the amount of energy the battery can currently store, energy-full-design indicates the original maximum amount of energy the battery could store, and capacity shows the percentage of remaining capacity compared to the original value.

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