On 31 May 2016 15:43:54 BST, Daniel Baluta <daniel.baluta@xxxxxxxxx> wrote: >On Sun, Mar 6, 2016 at 10:02 PM, Jonathan Cameron <jic23@xxxxxxxxxx> >wrote: >> This patch is in response to that of >> Gregor Boirie <gregor.boirie@xxxxxxxxxx> >> 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. >> > >Configfs part looks good to me. > >What happens with iio_loop_thread when changing the current trigger? >I'm not sure how it will be stopped. To change trigger the buffer will be disabled ultimately calling the state function with false. That calls kthread_stop and the loop should drop out with the tread exiting. Jonathan > >thanks, >Daniel. >-- >To unsubscribe from this list: send the line "unsubscribe linux-iio" in >the body of a message to majordomo@xxxxxxxxxxxxxxx >More majordomo info at http://vger.kernel.org/majordomo-info.html -- Sent from my Android device with K-9 Mail. Please excuse my brevity. -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
