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

[sashiko-bot@kernel.org]

> 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@rock-chips.com>

Sashiko has reviewed this patch and found no issues. It looks great!

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