From 7a60055f689cd45412503792dc206142d472573e Mon Sep 17 00:00:00 2001 From: Tim Crawford Date: Fri, 1 Mar 2024 11:40:37 -0700 Subject: [PATCH] docs: Update CSME note about S0ix/TGL-U CSME should be enabled when S0ix is used for power savings during suspend. TGL-U is just one case where we default as our TGL-U models do not support S3. Other models may use S0ix as well, such as darp8 and darp9 due to new batches just not working with S3 anymore [1]. [1]: https://github.com/system76/firmware-open/issues/507 Signed-off-by: Tim Crawford --- docs/intel-me.md | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-) diff --git a/docs/intel-me.md b/docs/intel-me.md index eacab93..7960a27 100644 --- a/docs/intel-me.md +++ b/docs/intel-me.md @@ -55,15 +55,18 @@ ME: Current Operation Mode : 0 ME: Error Code : 0 ``` -## Tiger Lake-U +## S0ix -Models using TGL-U processors default to having the IME enabled. TGL-U removes -support for S3 and requires S0ix. This requires all CPU, PCH, and PCIe devices -to have ACPI defined low power states. With S0ix, the CPU has numerous states -for low power, with the lowest being C10. In order to reach this C10 state, the -IME must report that it is in a low power state. Disabling the ME with the HAP -bit keeps the CPU in the C8 state. This nearly triples the power usage in S0ix -suspend, from around 1 watt to around 3 watts. +S0ix (Modern Standby, s2idle) requires all CPU, PCH, and PCIe devices to have +ACPI defined low power states. The CPU has numerous states for low power, with +the lowest being C10. In order to reach this C10 state, the CSME must report +that it is in a low power state. + +Disabling the CSME with the HAP bit or HECI command keeps the CPU in the C8 +state. This nearly triples the power usage in S0ix suspend, from around 1 watt +to around 3 watts. + +TGL-U removed support for S3 and requires S0ix. [wiki]: https://en.wikipedia.org/wiki/Intel_Management_Engine