i.MX8MM PCIe Controller Legacy PCI interrupts support

[yasunori_suzuki]

I'm developing the PCIe controller driver.
It needs to work the PCI device via the PCIe-PCI bridge.
The PCI device supports legacy PCI interrupts only.
The PCIe controller driver can't catch it's legacy PCI interrupts.

I have some questions.

Q1: Does PCIe controller of i.MX8MM support legacy PCI interrupts?

Q2: If PCIe controller of i.MX8MM support legacy PCI interrupts,
which GIC IRQs of i.MX8MM are the Legacy PCI interrupts assigned to?
I tried to use IRQ 122, IRQ 123, IRQ 124, IRQ 125 and IRQ 127.
But the PCIe controller driver couldn't cache the Legacy PCI interrupts.

Q3: If PCIe controller of i.MX8MM support legacy PCI interrupts,
Could you provide information about using legacy PCI interrupts?
I read i.MX8MM Reference Manual(IMX8MMRM.pdf). But I couldn't find it.

[weidong_sun · Accepted solution]

Hi,

Q1: Does PCIe controller of i.MX8MM support legacy PCI interrupts?

Yes, it does.

Q2: IRQ 122, IRQ 123, IRQ 124, IRQ 125 and IRQ 127 are used for PCIe interrupts, so no problem.

Q3: If PCIe controller of i.MX8MM support legacy PCI interrupts, Could you provide information about using legacy PCI interrupts?

You should add "pci=nomsi" to linux command line , which will cause all pcie device to work in legacy PCI interrupts mode. otherwise, msi mode.

Hope above information is helpful to you.

Have a nice day!

B.R,

Weidong

[yasunori_suzuki]

Thank you for your advice.
I can execute linux in no-msi mode.
And linux behavior helped my debugging.
At result developping drive can catch legacy PCI interrupt.