On 12/06/19 8:36 PM, Eugeniu Rosca wrote: > Hi Marc, > > Thanks for your comment. > > On Wed, Jun 12, 2019 at 11:17:10AM +0100, Marc Zyngier wrote: >> Eugeniu Rosca <erosca@xxxxxxxxxxxxxx> wrote: >>> On Tue, Jun 11, 2019 at 10:00:41AM +0100, Marc Zyngier wrote: > [..] >>>> We already have plenty of that in the tree, the canonical example >>>> probably being drivers/irqchip/irq-mtk-sysirq.c. It should be pretty >>>> easy to turn this driver into something more generic. >>> I don't think drivers/irqchip/irq-mtk-sysirq.c can serve the >>> use-case/purpose of this patch. The MTK driver seems to be dealing with >>> the polarity inversion of on-SoC interrupts which are routed to GiC, >>> whereas in this patch we are talking about an off-chip interrupt >>> wired to R-Car GPIO controller. >> And how different is that? The location of the interrupt source is >> pretty irrelevant here. > The main difference which I sense is that a driver like irq-mtk-sysirq > mostly (if not exclusively) deals with internal kernel implementation > detail (tuned via DT) whilst adding an inverter for GPIO IRQs raises > a whole bunch of new questions (e.g. how to arbitrate between > kernel-space and user-space IRQ polarity configuration?). > >> The point is that there is already a general >> scheme to deal with these "signal altering widgets", and that we >> should try to reuse at least the concept, if not the code. > Since Harish Jenny K N might be working on a new driver doing GPIO IRQ > inversion, I have CC-ed him as well to avoid any overlapping work. Sorry I am not completely aware of the background discussion. But here is the link to my proposal for new consumer driver to provide a new virtual gpio controller to configure the polarity of the gpio pins used by the userspace. https://www.spinics.net/lists/linux-gpio/msg39681.html > >>> It looks to me that the nice DTS sketch shared by Linus Walleij in [5] >>> might come closer to the concept proposed by Geert? FWIW, the >>> infrastructure/implementation to make this possible is still not >>> ready. >> Which looks like what I'm suggesting. > Then we are on the same page. Thanks. > >> M. >> >> -- >> Jazz is not dead, it just smells funny.
