[AMD Official Use Only - AMD Internal Distribution Only]
Hi Mani,
-----Original Message----- From: mani@kernel.org mani@kernel.org Sent: Wednesday, October 22, 2025 4:02 PM To: Havalige, Thippeswamy thippeswamy.havalige@amd.com Cc: Stefan Roese stefan.roese@mailbox.org; Bjorn Helgaas helgaas@kernel.org; Bandi, Ravi Kumar ravib@amazon.com; lpieralisi@kernel.org; bhelgaas@google.com; linux-pci@vger.kernel.org; kwilczynski@kernel.org; robh@kernel.org; Simek, Michal michal.simek@amd.com; linux-arm-kernel@lists.infradead.org; linux- kernel@vger.kernel.org; stable@vger.kernel.org; Sean Anderson sean.anderson@linux.dev Subject: Re: [PATCH v2] PCI: xilinx-xdma: Enable INTx interrupts
On Wed, Oct 22, 2025 at 10:08:44AM +0000, Havalige, Thippeswamy wrote:
[AMD Official Use Only - AMD Internal Distribution Only]
Hi Stefan,
-----Original Message----- From: Stefan Roese stefan.roese@mailbox.org Sent: Wednesday, October 22, 2025 3:29 PM To: mani@kernel.org Cc: Bjorn Helgaas helgaas@kernel.org; Bandi, Ravi Kumar ravib@amazon.com; Havalige, Thippeswamy thippeswamy.havalige@amd.com; lpieralisi@kernel.org; bhelgaas@google.com; linux-pci@vger.kernel.org; kwilczynski@kernel.org; robh@kernel.org; Simek, Michal michal.simek@amd.com; linux-arm- kernel@lists.infradead.org; linux-kernel@vger.kernel.org; stable@vger.kernel.org; Sean Anderson sean.anderson@linux.dev Subject: Re: [PATCH v2] PCI: xilinx-xdma: Enable INTx interrupts
On 10/22/25 11:55, mani@kernel.org wrote:
On Wed, Oct 22, 2025 at 08:59:19AM +0200, Stefan Roese wrote:
Hi Bjorn, Hi Ravi,
On 10/21/25 23:28, Bjorn Helgaas wrote:
On Tue, Oct 21, 2025 at 08:55:41PM +0000, Bandi, Ravi Kumar wrote: >> On Tue, Oct 21, 2025 at 05:46:17PM +0000, Bandi, Ravi Kumar
wrote:
>>>> On Oct 21, 2025, at 10:23 AM, Bjorn Helgaas >>>> helgaas@kernel.org
wrote:
>>>> On Sat, Sep 20, 2025 at 10:52:32PM +0000, Ravi Kumar Bandi
wrote:
>>>>> The pcie-xilinx-dma-pl driver does not enable INTx >>>>> interrupts after initializing the port, preventing INTx >>>>> interrupts from PCIe endpoints from flowing through the >>>>> Xilinx XDMA root port bridge. This issue affects kernel 6.6.0 and
later versions.
>>>>> >>>>> This patch allows INTx interrupts generated by PCIe >>>>> endpoints to flow through the root port. Tested the fix on >>>>> a board with two endpoints generating INTx interrupts. >>>>> Interrupts are properly detected and serviced. The >>>>> /proc/interrupts output >>>>> shows: >>>>> >>>>> [...] >>>>> 32: 320 0 pl_dma:RC-Event 16 Level 400000000.axi-
pcie,
azdrv
>>>>> 52: 470 0 pl_dma:RC-Event 16 Level 500000000.axi-
pcie,
azdrv
>>>>> [...]
First a comment on this IRQ logging:
These lines do NOT refer to the INTx IRQ(s) but the controller internal "events" (errors etc). Please see this log for INTx on my Versal platform with pci_irqd_intx_xlate added:
24: 0 0 pl_dma:RC-Event 0 Level LINK_DOWN 25: 0 0 pl_dma:RC-Event 3 Level HOT_RESET 26: 0 0 pl_dma:RC-Event 8 Level CFG_TIMEOUT 27: 0 0 pl_dma:RC-Event 9 Level CORRECTABLE 28: 0 0 pl_dma:RC-Event 10 Level NONFATAL 29: 0 0 pl_dma:RC-Event 11 Level FATAL 30: 0 0 pl_dma:RC-Event 20 Level SLV_UNSUPP 31: 0 0 pl_dma:RC-Event 21 Level SLV_UNEXP 32: 0 0 pl_dma:RC-Event 22 Level SLV_COMPL 33: 0 0 pl_dma:RC-Event 23 Level SLV_ERRP 34: 0 0 pl_dma:RC-Event 24 Level SLV_CMPABT 35: 0 0 pl_dma:RC-Event 25 Level SLV_ILLBUR 36: 0 0 pl_dma:RC-Event 26 Level MST_DECERR 37: 0 0 pl_dma:RC-Event 27 Level MST_SLVERR 38: 94 0 pl_dma:RC-Event 16 Level 84000000.axi-pcie 39: 94 0 pl_dma:INTx 0 Level nvme0q0, nvme0q1
The last line shows the INTx IRQs here ('pl_dma:INTx' vs 'pl_dma:RC- Event').
More below...
>>>>> >>>>> Changes since v1:: >>>>> - Fixed commit message per reviewer's comments >>>>> >>>>> Fixes: 8d786149d78c ("PCI: xilinx-xdma: Add Xilinx XDMA >>>>> Root Port driver") >>>>> Cc: stable@vger.kernel.org >>>>> Signed-off-by: Ravi Kumar Bandi ravib@amazon.com >>>> >>>> Hi Ravi, obviously you tested this, but I don't know how to >>>> reconcile this with Stefan's INTx fix at >>>> https://lore.kernel.org/r/20251021154322.973640-1-
stefan.roese@m
>>>> ailbox.org >>>> >>>> Does Stefan's fix need to be squashed into this patch? >>> >>> Sure, we can squash Stefan’s fix into this. >> >> I know we *can* squash them. >> >> I want to know why things worked for you and Stefan when they >> *weren't* squashed: >> >> - Why did INTx work for you even without Stefan's patch. Did you >> get INTx interrupts but not the right ones, e.g., did the device >> signal INTA but it was received as INTB? > > I saw that interrupts were being generated by the endpoint > device, but I didn’t specifically check if they were correctly > translated in the controller. I noticed that the new driver > wasn't explicitly enabling the interrupts, so my first approach > was to enable them, which helped the interrupts flow through.
OK, I'll assume the interrupts happened but the driver might not have been able to handle them correctly, e.g., it was prepared for INTA but got INTB or similar.
>> - Why did Stefan's patch work for him even without your patch.
How
>> could Stefan's INTx work without the CSR writes to enable >> interrupts? > > I'm not entirely sure if there are any other dependencies in > the FPGA bitstream. I'll investigate further and get back to you.
Stefan clarified in a private message that he had applied your patch first, so this mystery is solved.
Yes. I applied Ravi's patch first and still got no INTx delivered to the nvme driver. That's what me triggered to dig deeper here and resulted in this v2 patch with pci_irqd_intx_xlate added.
BTW: I re-tested just now w/o Ravi's patch and the INTx worked. Still I think Ravi's patch is valid and should be applied...
How come INTx is working without the patch from Ravi which enabled INTx routing in the controller? Was it enabled by default in the hardware?
Yes, this is my best guess right now. I could double-check here, but IMHO it makes sense to enable it "manually" as done with Ravi's patch to not rely on this default setup at all.
Hardware doesn't enable this bits by default, INTx didn't work since there is a
miss match in the DT property which doesn't require pci_irqd_intx_xlate.
interrupt-map = <0 0 0 1 &pcie_intc_0 0>, <0 0 0 2 &pcie_intc_0 1>, <0 0 0 3 &pcie_intc_0 2>, <0 0 0 4 &pcie_intc_0 3>;
Ok. This makes me believe that we do not need Stefan's patch [1] and need just this patch from Ravi.
- Mani
[1] https://lore.kernel.org/linux-pci/20251021154322.973640-1- stefan.roese@mailbox.org/
We even don’t need ravi patch, as we have tested this at our end it works fine by just updating interrupt-map Property. We need to now understand the difference in design.
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