Re: [PATCH] i.MX6 PCIe: Fix imx6_pcie_deassert_core_reset() polarity

From: Roberto Fichera
Date: Tue Mar 29 2016 - 12:23:16 EST

On 03/29/2016 05:10 PM, 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.
> I would also think this was something IMX specific, but I really don't
> see any codepaths in pci-imx6.c that would cause that: a driver
> requesting a legacy PCI would get a GIC interrupt which is handled by
> the IMX6 gpc interrupt controller.
> Any dra7xxx, exynos, spear13xx, keystone, layerscape, hisi, qcom SoC
> users of designware PCIe core out there that can verify PCI MSI and
> legacy are both working at the same time?
> Lucas is the expert here and I believe he has the documentation for
> the designware core that Freescale doens't provide with the IMX6
> documentation so hopefully he can provide some insight. He's the one
> that has authored all the MSI support and has been using it.
> 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.

Don't know if I'm facing similar problem, however devices connected in miniPCI slot behind
a PCIe-to-PCI bridge (MSI is disabled) using INTA all is working ok, including shared IRQ.
In case of INTB will not work, and the GIC irq quite often get stuck.