On 29/03/17 10:59, Brendan Higgins wrote: > The main reason I took this approach is just because I thought it was > cleaner from the perspective of the busses which are totally > independent (except for the fact that they share a single hardware > interrupt). > > I did not make any measurements, so I doubt that I have anything to > add that you don't already know. I saw other usages of chained > interrupts that do the same thing (scan a "status" register and use > them to make software interrupts) and I thought that is basically what > the dummy irq chip code is for. The only thing I thought I was doing > that was novel was actually breaking out the dummy irqchip into its > own driver; it is not my idea, but I do think makes it a lot cleaner. > Nevertheless, it should be cheap in terms of number of instructions; > the most expensive part looks like looking up the mapping. In any > case, I think the low hanging fruit here is supporting buffering or > DMA, like Ben suggested. > > To address the comment on being over engineered: outside of the init > function (which would exist regardless of how we do this, if not here > then in the I2C driver); the code is actually pretty small and > generic. > > All that being said, it would not be very hard to do this without > using the dummy irqchip code and it would definitely be smaller in > terms of indirection and space used, but I think the code would > actually be more complicated to read. We would be going back to having > an I2C controller along with the I2C busses; where all the I2C > controller does is read the IRQ register and then call the appropriate > bus irq handler, which looks a lot like a dummy irqchip. As long as you're happy with the performance and the restrictions that come attached to the HW, I'm happy to take the irqchip patches. Thanks, M. -- Jazz is not dead. It just smells funny... -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
