On Tuesday 29 March 2016 08:10:08 Tim Harvey wrote: > Arnd, > > Right, on the IMX the MSI interrupt is GIC-120 which is also the > legacy INTD and I do see that if I happen to put a radio in a slot > where due to swizzling its pin1 becomes INTD (GIC-120) the interrupt > does fire and the device works. Any other slot using GIC-123 (INTA), > GIC-122 (INTB), or GIC-121 (INTC) never fires so its very possible > that something in the designware core is masking out the legacy irqs. Interesting. I was actually expecting the opposite here, having the IRQs only work if they are not IntD. > I typically advise our users to 'not' enable MSI because > architecturally you can spread 4 distinct legacy irq's across CPU's > better than a single shared irq. That is a very good point, I never understood why we want to enable MSI support on any PCI host bridge that just forwards all MSIs to a single IRQ line. Originally MSI was meant as a performance feature, but there is nothing in this setup that makes things go faster, and several things that make it go slower. I would still hope that with disabling MSI support in just the i.MX driver (as in the trivial patch I suggested trying, or by reverting Lucas' d1dc9749a5b8 patch) will make things just work. If not, we may need to change the pcie-designware driver as well, so it doesn't try to enable MSI on its own. Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
