https://bugzilla.kernel.org/show_bug.cgi?id=219044
Bug ID: 219044
Summary: cppc_acpi fails to detect _CPC support
Product: ACPI
Version: 2.5
Hardware: AMD
OS: Linux
Status: NEW
Severity: normal
Priority: P3
Component: Power-Processor
Assignee: acpi_power-proces...@kernel-bugs.osdl.org
Reporter: nicolas.grange...@gmail.com
Regression: No
acpi_cppc seems to fail to detect _CPC support on Lenovo Yoga Pro 7 14AHP9.
This causes linux to fall back to acpi pstate by default or to discard epp
support if amd_pstate=active is passed on the cmdline.
When booting with "amd_pstate=active amd_pstate.dyndbg=+p cppc_acpi.dyndbg=+p
debug" on the command line, dmesg[1] contains the following lines about CPC:
[ 0.437698] ACPI CPPC: Parsed CPC struct for CPU: 0
...
[ 0.502121] ACPI CPPC: _CPC in PCC is not supported
On windows, the hwinfo tool mentions CPPC support (the interface is confusing,
I can launch it again with guidance on what to look for). It also reports the
CPU core frequencies go as low as 1GHz with a high percentage in C6 state. On
linux, acpi pstate can only reach 1.6GHz minimum, with amd_pstate=active,
`cpupower monitor` reports frequencies above 2GHz.
In the ACPI tables[2], _CPC entries are present[3].
The bios changelog[4] mentions "1.Follow AMD's suggest, Disabling DVFS
temporarily to mitigate the BSOD on UUT with Micron memory." which is unclear
to me.
System information:
- Laptop model: Lenovo Yoga Pro 7 14AHP9
- BIOS version: 1.16 (NCCN16WW 02/02/2024)
- Processor: AMD Ryzen 7 8845HS
- Kernel: 6.9.8 (Arch linux)
[1]
https://gist.github.com/nlgranger/9eae8ea594930e605f22d1ae6ecbf49f#file-dmesg
[2]
https://gist.github.com/nlgranger/9eae8ea594930e605f22d1ae6ecbf49f#file-acpidump
[3]
https://gist.github.com/nlgranger/9eae8ea594930e605f22d1ae6ecbf49f#file-ssdt11-dsl-L380
[4] https://download.lenovo.com/consumer/mobiles/nccn16ww.txt
--
You may reply to this email to add a comment.
You are receiving this mail because:
You are watching the assignee of the bug.
_______________________________________________
acpi-bugzilla mailing list
acpi-bugzilla@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/acpi-bugzilla
