Re: [PATCH] PCI: dwc: ep: Cache MSI outbound iATU mapping

[Niklas Cassel <cassel@kernel.org>]

On Mon, Dec 22, 2025 at 03:28:30PM +0530, Manivannan Sadhasivam wrote:
> 
> > Use the MSIX doorbell method which will not use iATU at all,
> > dw_pcie_ep_raise_msix_irq_doorbell().
> > 
> 
> I think this is the safe bet since this feature doesn't seem like an optional
> one.
> 
> Niklas, if you can just fix MSI in this patch and leave out MSI-X for the vendor
> drivers to transition to doorbell, I'm OK to merge it. Otherwise, I don't know
> how you can reliably fix MSI-X generation with AXI slave interface.

FWIW, I did try to simply change:

diff --git a/drivers/pci/controller/dwc/pcie-dw-rockchip.c b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
index 8f2cc1ef25e3..00770f9786e3 100644
--- a/drivers/pci/controller/dwc/pcie-dw-rockchip.c
+++ b/drivers/pci/controller/dwc/pcie-dw-rockchip.c
@@ -319,7 +319,8 @@ static int rockchip_pcie_raise_irq(struct dw_pcie_ep *ep, u8 func_no,
        case PCI_IRQ_MSI:
                return dw_pcie_ep_raise_msi_irq(ep, func_no, interrupt_num);
        case PCI_IRQ_MSIX:
-               return dw_pcie_ep_raise_msix_irq(ep, func_no, interrupt_num);
+               return dw_pcie_ep_raise_msix_irq_doorbell(ep, func_no,
+                                                         interrupt_num);
        default:
                dev_err(pci->dev, "UNKNOWN IRQ type\n");
        }


For the pcie-dw-rockchip driver, but it is not working:
[  130.042849] nvme nvme0: I/O tag 0 (1000) QID 0 timeout, completion polled

Without this change, things work.

Perhaps this feature is not an optional one, but at least we will require
more changes than a simple one liner.


Kind regards,
Niklas