This patch is in response to that of
Gregor Boirie <gregor.boirie@parrot.com>
who proposed using a tight kthread within a device driver (be it with the
support factored out into a helper library) in order to basically spin as
fast as possible.
It is meant as a talking point rather than a formal proposal of the code
(though we are heading towards that I think).
Also gives people some working code to mess around with.
I proposed that this could be done with a trigger with a few constraints
and this is the proof (be it ugly) of that.
There are some constraints though, some of which we would want to relax
if this were to move forward.
* Will only run the thread part of the registered pollfunc. This is to
avoid the overhead of jumping in and out of interrupt context. Is the
overhead significant? Not certain but feels like it should be!
* This limitation precludes any device that 'must' do some work in
interrupt context. However, that is true of few if any drivers and
I suspect that any that do will be restricted to using triggers they
provide themselves. Usually we have a top half mainly to grab a
timestamp as soon after the dataready type signal as possible.
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Acked-by: Daniel Baluta <daniel.baluta@intel.com>
This patch registers a new IIO software trigger interrupt source
based on high resolution timers.
Notice that if configfs is enabled we create sampling_frequency
attribute allowing users to change hrtimer period (1/sampling_frequency).
The IIO hrtimer trigger has a long history, this patch is based on
an older version from Marten and Lars-Peter.
Signed-off-by: Marten Svanfeldt <marten@intuitiveaerial.com>
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Daniel Baluta <daniel.baluta@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Keeping Makefile and Kconfig entries in alphabetical order usually works better
than just appending new entries at the end, since it reduces the amount of
conflicts. This patch adds a comment to the IIO Kconfig and Makefile files to
document that the entries should be kept in alphabetical order.
Also reorder those entries which weren't in alphabetical order yet.
Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
This is now a very simple trigger indeed but useful in many common cases.
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Reviewed-by: Lars-Peter Clausen <lars@metafoo.de>
This simple driver is rather useful. No issues about its interface
have been raised for some time hence the proposal to move it out
of staging.
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
Jonathan Cameron