On 08/04/2015 07:34 AM, Shubhrajyoti Datta wrote: > On Fri, Jul 24, 2015 at 6:08 PM, Lars-Peter Clausen <lars@xxxxxxxxxx> wrote: >> Hi, >> >> Sorry, but I don't think this patch has been sufficiently tested against a >> mainline kernel. The driver wont even probe the way it is right now. >> >> On 07/21/2015 01:14 AM, Xander Huff wrote: >>> >>> The driver currently registers a pair of irq handlers using >>> request_threaded_irq(), however the synchronization mechanism between the >>> hardirq and the threadedirq handler is a regular spinlock. >> >> >> If everything runs in threaded context we don't really need the spinlock >> anymore and can use the mutex throughout. > > that should be better from the performance point of view. > >> >>> >>> Unfortunately, this breaks PREEMPT_RT builds, where a spinlock can sleep, >>> and is thus not able to be acquired from a hardirq handler. This patch >>> gets >>> rid of the hardirq handler and pushes all interrupt handling into the >>> threaded context. >> >> >> We actually might as well run everything in the hardirq handler (which will >> be threaded in PREEMPT_RT). The reason why we have the threaded handler is >> because xadc_handle_event() used to sleep, but it doesn't do this anymore. > > The point is why have the hard irq. If we use hardirq then not mutex > can be used and spinlock will > be busy. Well there is no need to use a threaded IRQ. The interrupt handler is quite small and doesn't take too much time and doesn't have any delays or sleeps in it either. -- 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
