Linux not suspending issue fixed

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First of all to gain a thorough understanding about the issue, let’s cover all ACPI sleep states (S0 to S5):

1. S0 State (Working state)

• This is the normal operating state of the computer.
• The CPU is fully powered and executing instructions.
• All peripherals and components are operational.
• Power consumption is at its highest in this state as the system is actively running.

2. S1 State (Standby):

• Also known as the “Standby state” or “Suspend to RAM.”
• In S1, the CPU stops executing instructions to save power.
• The CPU maintains its state (registers and cache) so it can quickly resume processing.
• Power is still supplied to RAM and some other components.
• This state allows for a quick wake-up time (usually a few seconds).
• Power consumption is reduced compared to S0, but not as low as deeper sleep states.

3. S2 State (Sleep):

• Also known as the “Sleep state” or “Suspend to RAM.”
• S2 builds upon S1 by further reducing power consumption.
• In S2, more components are powered down compared to S1.
• The CPU is powered down, and its state (registers and cache) is saved to RAM.
• This state consumes less power than S1.
• It takes longer to wake up from S2 compared to S1 (typically several seconds to resume).

4. S3 State (Standby):

• Also known as the “Standby state” or “Suspend to RAM.”
• S3 is a deeper sleep state where most components are powered down.
• The CPU is powered off, and its state (registers and cache) is saved to RAM.
• RAM remains powered to retain data, but other components such as the CPU and peripherals are in a low-power state or completely powered off.
• This state consumes significantly less power than S2.
• It takes longer to wake up from S3 compared to S1 and S2 (typically several seconds to resume).

5. S4 State (Hibernate):

• Also known as the “Hibernate state” or “Suspend to Disk.”
• In S4, the system saves the current state (including the contents of RAM) to the hard disk or another non-volatile storage device.
• The system then completely powers off, consuming no power except for a small amount needed to monitor the power button or other wake-up triggers.
• This state is useful for longer periods of inactivity as it allows the system to save its state indefinitely without requiring continuous power.
• Resume from S4 (hibernate) state is slower than from S1 to S3 because it involves reading the saved state from disk back into RAM.

6. S5 State (Soft Off):

• Also known as the “Soft Off state” or “Mechanical Off.”
• S5 is the state where the system is completely powered off.
• No power is supplied to the system except for minimal circuitry to detect and respond to the power button press or other wake-up events.
• The state of the system and any running applications or data is not preserved; it requires a full boot process to resume operation.
• This state consumes the least amount of power since the system is essentially turned off.

These ACPI sleep states (S0 to S5) allow a computer system to manage power consumption based on its activity level, balancing the need for immediate responsiveness with power savings during periods of inactivity.

Fix explained

Below mentioned steps are for Ubuntu 22.04. If you are using a different distro, please update your commands accordingly.

By default when you click on suspend, the system goes to the S0 standby state.

To manually override this, execute the following steps:

sudo vim /etc/default/grub

Press i to go to insert mode and add the following line:

GRUB_CMDLINE_LINUX_DEFAULT=“mem_sleep_default=deep”

If some values already exist for the above variable, include the configuration as a space separated value along with the other configurations.

sudo update-grub

sudo reboot now

This will fix your issue. But if your issue still persists, check your BIOS settings with regard to power states.