On Tue, Dec 8, 2020 at 3:07 PM Enrico Weigelt, metux IT consult <lkml@xxxxxxxxx> wrote: > I've been looking for some more direct notification callback for gpio > consumers: here the consumer would register itself as a listener on > some gpio_desc and called back when something changes (with data what > exactly changed, eg. "gpio #3 input switched to high"). > > Seems we currently just have the indirect path via interrupts. I don't know how indirect it is, it seems pretty direct to me. The subsystem was designed in response to how the hardware in front of the developers worked. So far we have had: - Cascaded interrupts - Dedicated (hieararchical) interrupts - Message Signalled Interrupts And if you now bring something else to the show then it's not like the subsystem was designed for some abstract quality such as generic notification of events that occurred, all practical instances have been around actual IRQs and that is why it is using struct irq_chip. What we need to understand is if your new usecase is an outlier so it is simplest modeled by a "mock" irq_chip or we have to design something new altogether like notifications on changes. I suspect irq_chip would be best because all drivers using GPIOs for interrupts are expecting interrupts, and it would be an enormous task to change them all and really annoying to create a new mechanism on the side. Yours, Linus Walleij _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/virtualization
