Hi Jonathan,
The Android user space has some capability to ask the supported hardware
to enable buffering in hardware.
I don't think that we can achieve this by current ABI. Do you want me
to propose new ABI?
"
Android batch mode:
batch(int handle, int flags, int64_t period_ns, int64_t max_report_latency)
Enabling batch mode for a given sensor sets the delay between events.
max_report_latency sets the maximum time by which events can be delayed
and batched together before being reported to the applications. A value
of zero disables batch mode for the given sensor. The period_ns
parameter is equivalent to calling setDelay() -- this function both
enables or disables the batch mode AND sets the event's period in
nanoseconds. See setDelay() for a detailed explanation of the period_ns
parameter.
In non-batch mode, all sensor events must be reported as soon as they
are detected. For example, an accelerometer activated at 50Hz will
trigger interrupts 50 times per second.
While in batch mode, sensor events do not need to be reported as soon as
they are detected. They can be temporarily stored and reported in
batches, as long as no event is delayed by more than maxReportingLatency
nanoseconds. That is, all events since the previous batch are recorded
and returned at once. This reduces the amount of interrupts sent to the
SoC and allows the SoC to switch to a lower power mode (idle) while the
sensor is capturing and batching data.
setDelay() is not affected and it behaves as usual.
Each event has a timestamp associated with it. The timestamp must be
accurate and correspond to the time at which the event physically happened.
Batching does not modify the behavior of poll(): batches from different
sensors can be interleaved and split. As usual, all events from the same
sensor are time-ordered.
"
Thanks,
Srinivas
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