enter_freeze() callback is expected atleast to do the same as enter()
but it has to guarantee that interrupts aren't enabled at any point
in its execution, as the tick is frozen.
CPUs execute ->enter_freeze with the local tick or entire timekeeping
suspended, so it must not re-enable interrupts at any point (even
temporarily) or attempt to change states of clock event devices.
It will be called when the system goes to suspend-to-idle and will
reduce power usage because CPUs won't be awaken for unnecessary IRQs
(i.e. woken up only on IRQs from "wakeup sources")
We can reuse the same code for both the enter() and enter_freeze()
callbacks as along as they don't re-enable interrupts. Only "coupled"
cpuidle mechanism enables interrupts and doing that with timekeeping
suspended is generally not safe.
Since this generic DT based idle driver doesn't support "coupled"
states, it is safe to assume that the interrupts are not re-enabled.
This patch assign enter_freeze to same as enter callback function which
helps to save power without any intermittent spurious wakeups from
suspend-to-idle.
Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Tested-by: Andy Gross <andy.gross@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
On ARM machines, where generally speaking the idle state numbering has
no fixed and standard meaning it is useful to provide a description
of the idle state inner workings for benchmarking and monitoring purposes.
This patch adds a property to the idle states bindings that if present
gives platform firmware a means of describing the idle state and export
the string description to user space.
The patch updates the DT parsing code accordingly to take the description,
if present, into consideration.
Acked-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
On some platforms the device tree bindings must provide the kernel
with a status flag for idle states, that defines whether the idle
state is operational or not in the current configuration.
This patch adds a status property to the ARM idle states compliant
with ePAPR v1.1 and updates the DT parsing code accordingly.
Acked-by: Kevin Hilman <khilman@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
The only place where the time is invalid is when the ACPI_CSTATE_FFH entry
method is not set. Otherwise for all the drivers, the time can be correctly
measured.
Instead of duplicating the CPUIDLE_FLAG_TIME_VALID flag in all the drivers
for all the states, just invert the logic by replacing it by the flag
CPUIDLE_FLAG_TIME_INVALID, hence we can set this flag only for the acpi idle
driver, remove the former flag from all the drivers and invert the logic with
this flag in the different governor.
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
On most common ARM systems, the low-power states a CPU can be put into are
not discoverable in HW and require device tree bindings to describe
power down suspend operations and idle states parameters.
In order to enable DT based idle states and configure idle drivers, this
patch implements the bulk infrastructure required to parse the device tree
idle states bindings and initialize the corresponding CPUidle driver states
data.
The parsing API accepts a start index that defines the first idle state
that should be initialized by the parsing code in order to give new and
legacy driver flexibility over which states should be parsed using the
new DT mechanism.
The idle states node(s) is obtained from the phandle list of the first cpu
in the driver cpumask; the kernel checks that the idle state node phandle
is the same for all CPUs in the driver cpumask before declaring the idle state
as valid and start parsing its content.
The idle state enter function pointer is initialized through DT match
structures passed in by the CPUidle driver, so that ARM legacy code can
cope with platform specific idle entry method based on compatible
string matching and the code used to initialize the enter function pointer
can be moved to the DT generic layer.
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Sudeep Holla