[PATCH] PCI: dw-rockchip: Enable INTx affinity support

[Manivannan Sadhasivam]

+ Thomas

On Tue, Sep 29, 2026 at 02:54:58PM +0800, Shawn Lin wrote:
> Leverage the interrupt redirection infrastructure to enable CPU
> affinity support for the legacy INTx interrupts. The INTx virqs are
> demultiplexed by the chained handler of the "legacy" interrupt, whose
> affinity cannot be changed, so affinity control for the INTx virqs is
> achieved by redirecting the handler to run in IRQ work context on the
> target CPU.
> 
> Mask the INTx source in .irq_pre_redirect() before the handler is
> redirected: the legacy interrupt is level triggered, so an unmasked
> line would keep re-firing the chained interrupt until the redirected
> handler runs.
> 
> Same approach as the DesignWare core, commit eaf290c404f7c39f2 ("PCI:
> dwc: Enable MSI affinity support").
> 
> Test was done on RK3588 EVB1 board with an NVMe with pci=nomsi
> parameter. The /proc/interrupts columns are trimmed for brevity.
> 
>   # cat /proc/interrupts | grep INTx
>   51:  137 0 0 0 0 0 0 0 INTx 0 Edge PCIe PME, nvme0q0, nvme0q1
>   # echo 10 > /proc/irq/51/smp_affinity
>   # dd if=/dev/nvme0n1p1 of=/dev/null bs=1M count=200
>   200+0 records in
>   200+0 records out
>   209715200 bytes (210 MB, 200 MiB) copied, 0.182021 s, 1.2 GB/s
>   # cat /proc/interrupts | grep INTx
>   51:  137 0 0 0 946 0 0 0 INTx 0 Edge PCIe PME, nvme0q0, nvme0q1
> 
> Signed-off-by: Shawn Lin <shawn.lin at rock-chips.com>

I'd like to get an Ack from Thomas for this patch since I'm not an irqchip
expert to decipher whether this patch is valid or not.

If this patch is valid and INTx affinity can be enabled like this, I'd like to
extend this to other RC drivers exposing INTx irqchip.

- Mani

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