Re: [PATCH v2] PCI: pcie-xilinx-dma-pl: Fix off-by-one INTx IRQ handling

[Bjorn Helgaas <helgaas@kernel.org>]

On Tue, Oct 21, 2025 at 05:43:22PM +0200, Stefan Roese wrote:
> While testing with NVMe drives connected to the Versal QDMA PL PCIe RP
> on our platform I noticed that with MSI disabled (e.g. via pci=nomsi)
> the NVMe interrupts are not delivered to the host CPU resulting in
> timeouts while probing.
> 
> Debugging has shown, that the hwirq numbers passed to this device driver
> (1...4, 1=INTA etc) need to get adjusted to match the numbers in the
> controller registers bits (0...3).
> 
> This patch now adds pci_irqd_intx_xlate to the INTx IRQ domain ops,
> handling this IRQ number translation correctly.

s/pcie-xilinx-dma-pl:/xilinx-xdma:/  # in subject
s/has shown, that/has shown that/
s/This patch now adds/Add/
s/pci_irqd_intx_xlate/pci_irqd_intx_xlate()/

We'll do this when applying, no need to repost for this.

I wonder how many other drivers have this issue.
pci_irqd_intx_xlate() is used only by:

  dwc/pci-dra7xx.c
  pcie-altera.c
  pcie-xilinx-nwl.c
  pcie-xilinx.c
  pcie-xilinx-dma-pl.c   # this patch

Is there something different about these drivers that means they need
it when all the others don't?

> Signed-off-by: Stefan Roese <stefan.roese@mailbox.org>
> Cc: Sean Anderson <sean.anderson@linux.dev>
> Cc: Manivannan Sadhasivam <mani@kernel.org>
> Cc: Ravi Kumar Bandi <ravib@amazon.com>
> Cc: Thippeswamy Havalige <thippeswamy.havalige@amd.com>
> Cc: Michal Simek <michal.simek@amd.com>
> Cc: Bjorn Helgaas <bhelgaas@google.com>
> ---
> v2:
> - Use pci_irqd_intx_xlate to handle this IRQ number translation as suggested
>   by Sean (thanks again)
> 
>  drivers/pci/controller/pcie-xilinx-dma-pl.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/pci/controller/pcie-xilinx-dma-pl.c b/drivers/pci/controller/pcie-xilinx-dma-pl.c
> index 84888eda990b2..80095457ec531 100644
> --- a/drivers/pci/controller/pcie-xilinx-dma-pl.c
> +++ b/drivers/pci/controller/pcie-xilinx-dma-pl.c
> @@ -370,6 +370,7 @@ static int xilinx_pl_dma_pcie_intx_map(struct irq_domain *domain,
>  /* INTx IRQ Domain operations */
>  static const struct irq_domain_ops intx_domain_ops = {
>  	.map = xilinx_pl_dma_pcie_intx_map,
> +	.xlate = pci_irqd_intx_xlate,
>  };
>  
>  static irqreturn_t xilinx_pl_dma_pcie_msi_handler_high(int irq, void *args)
> -- 
> 2.51.1
>