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SubjectRe: [PATCH 6/6] PSCI: cpuidle: Refactor CPU suspend power_state parameter handling
On Mon, 22 Jul 2019 at 17:38, Lorenzo Pieralisi
<lorenzo.pieralisi@arm.com> wrote:
>
> Current PSCI code handles idle state entry through the
> psci_cpu_suspend_enter() API, that takes an idle state index as a
> parameter and convert the index into a previously initialized
> power_state parameter before calling the PSCI.CPU_SUSPEND() with it.
>
> This is unwieldly, since it forces the PSCI firmware layer to keep track
> of power_state parameter for every idle state so that the
> index->power_state conversion can be made in the PSCI firmware layer
> instead of the CPUidle driver implementations.
>
> Move the power_state handling out of drivers/firmware/psci
> into the respective ACPI/DT PSCI CPUidle backends and convert
> the psci_cpu_suspend_enter() API to get the power_state
> parameter as input, which makes it closer to its firmware
> interface PSCI.CPU_SUSPEND() API.
>
> A notable side effect is that the PSCI ACPI/DT CPUidle backends
> now can directly handle (and if needed update) power_state
> parameters before handing them over to the PSCI firmware
> interface to trigger PSCI.CPU_SUSPEND() calls.
>
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Ulf Hansson <ulf.hansson@linaro.org>
> Cc: Sudeep Holla <sudeep.holla@arm.com>
> Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
> ---
> arch/arm64/kernel/cpuidle.c | 47 +++++++++-
> drivers/cpuidle/cpuidle-psci.c | 87 +++++++++++++++++-
> drivers/firmware/psci/psci.c | 158 ++-------------------------------
> include/linux/cpuidle.h | 17 +++-
> include/linux/psci.h | 4 +-
> 5 files changed, 153 insertions(+), 160 deletions(-)
>
> diff --git a/arch/arm64/kernel/cpuidle.c b/arch/arm64/kernel/cpuidle.c
> index 4bcd1bca0dfc..e4d6af2fdec7 100644
> --- a/arch/arm64/kernel/cpuidle.c
> +++ b/arch/arm64/kernel/cpuidle.c
> @@ -47,6 +47,44 @@ int arm_cpuidle_suspend(int index)
>
> #define ARM64_LPI_IS_RETENTION_STATE(arch_flags) (!(arch_flags))
>
> +static int psci_acpi_cpu_init_idle(unsigned int cpu)
> +{
> + int i, count;
> + struct acpi_lpi_state *lpi;
> + struct acpi_processor *pr = per_cpu(processors, cpu);
> +
> + /*
> + * If the PSCI cpu_suspend function hook has not been initialized
> + * idle states must not be enabled, so bail out
> + */
> + if (!psci_ops.cpu_suspend)
> + return -EOPNOTSUPP;
> +
> + if (unlikely(!pr || !pr->flags.has_lpi))
> + return -EINVAL;
> +
> + count = pr->power.count - 1;
> + if (count <= 0)
> + return -ENODEV;
> +
> + for (i = 0; i < count; i++) {
> + u32 state;
> +
> + lpi = &pr->power.lpi_states[i + 1];
> + /*
> + * Only bits[31:0] represent a PSCI power_state while
> + * bits[63:32] must be 0x0 as per ARM ACPI FFH Specification
> + */
> + state = lpi->address;
> + if (!psci_power_state_is_valid(state)) {
> + pr_warn("Invalid PSCI power state %#x\n", state);
> + return -EINVAL;
> + }
> + }
> +
> + return 0;
> +}
> +
> int acpi_processor_ffh_lpi_probe(unsigned int cpu)
> {
> return psci_acpi_cpu_init_idle(cpu);
> @@ -54,10 +92,13 @@ int acpi_processor_ffh_lpi_probe(unsigned int cpu)
>
> int acpi_processor_ffh_lpi_enter(struct acpi_lpi_state *lpi)
> {
> + u32 state = lpi->address;
> +
> if (ARM64_LPI_IS_RETENTION_STATE(lpi->arch_flags))
> - return CPU_PM_CPU_IDLE_ENTER_RETENTION(psci_cpu_suspend_enter,
> - lpi->index);
> + return CPU_PM_CPU_IDLE_ENTER_RETENTION_PARAM(psci_cpu_suspend_enter,
> + lpi->index, state);
> else
> - return CPU_PM_CPU_IDLE_ENTER(psci_cpu_suspend_enter, lpi->index);
> + return CPU_PM_CPU_IDLE_ENTER_PARAM(psci_cpu_suspend_enter,
> + lpi->index, state);
> }

I am not sure where the acpi+psci cpuidle code really belongs. Perhaps
some code should be moved into separate acpi+psci cpuidle driver?

In any case and whatever makes sense, it can be done on top of the
current series.

[...]

Kind regards
Uffe

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