| Message ID | 20220225190646.1045695-1-mario.limonciello@amd.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Avoid enabling LPI on non-ARM | expand |
On Fri, Feb 25, 2022 at 8:11 PM Mario Limonciello <mario.limonciello@amd.com> wrote: > > On some AMD platforms the platform _OSC negotiation will lead to > `osc_pc_lpi_support_confirmed` being set and because the ACPI tables are > populated with `_LPI` entries the kernel will attempt to enable LPI. > > On non-ARM kernels LPI is not supported and both > `acpi_processor_ffh_lpi_probe` and > `acpi_processor_ffh_lpi_enter` will return error codes. > > When this happens there is no recourse though; the cpuidle code does > not switch to `_CST` mode, but rather it will continue to behave as though > LPI has been enabled and the CPU will remain in a high power state. > > This patch series shifts the checks around while enabling LPI to detect > this situation and let the system continue to set up in _CST mode. > > Link to v1: https://lore.kernel.org/linux-acpi/20220225031255.3647599-1-mario.limonciello@amd.com/T/#m90282a6e29c334d14b2854a27d7225fc57a22aa6 > > Mario Limonciello (2): > PSCI: cpuidle: Move the `has_lpi` check to the beginning of the > function > ACPI: processor idle: Check for architectural support for LPI > > arch/arm64/kernel/cpuidle.c | 6 +++--- > drivers/acpi/processor_idle.c | 15 ++++++++++----- > 2 files changed, 13 insertions(+), 8 deletions(-) > > -- Both patches in the series applied as 5.18 material, thanks!
On some AMD platforms the platform _OSC negotiation will lead to `osc_pc_lpi_support_confirmed` being set and because the ACPI tables are populated with `_LPI` entries the kernel will attempt to enable LPI. On non-ARM kernels LPI is not supported and both `acpi_processor_ffh_lpi_probe` and `acpi_processor_ffh_lpi_enter` will return error codes. When this happens there is no recourse though; the cpuidle code does not switch to `_CST` mode, but rather it will continue to behave as though LPI has been enabled and the CPU will remain in a high power state. This patch series shifts the checks around while enabling LPI to detect this situation and let the system continue to set up in _CST mode. Link to v1: https://lore.kernel.org/linux-acpi/20220225031255.3647599-1-mario.limonciello@amd.com/T/#m90282a6e29c334d14b2854a27d7225fc57a22aa6 Mario Limonciello (2): PSCI: cpuidle: Move the `has_lpi` check to the beginning of the function ACPI: processor idle: Check for architectural support for LPI arch/arm64/kernel/cpuidle.c | 6 +++--- drivers/acpi/processor_idle.c | 15 ++++++++++----- 2 files changed, 13 insertions(+), 8 deletions(-)