Re: [PATCH] dmaengine: dw-edma: Mark emulated IRQ as level-triggered

[Manivannan Sadhasivam]

On Fri, Jul 31, 2026 at 01:07:01AM +0900, Koichiro Den wrote:
> The interrupt-emulation virtual IRQ uses handle_level_irq(), but the IRQ
> descriptor has not been marked with IRQ_LEVEL.
> 
> The interrupt emulation is somewhat unusual: the eDMA interrupt handlers
> dispatch the virtual IRQ for every edma_int[] interrupt because software
> cannot reliably tell an interrupt-emulation event from one caused solely
> by DONE/ABORT status. If an interrupt arrives before the doorbell
> handler is registered for the virtual IRQ, the IRQ core marks it
> pending. When the IRQ is later started, check_irq_resend() treats it as
> non-level and replays the pending interrupt, causing the newly
> registered handler to run for a stale event.
> 
> Mark the virtual IRQ with IRQ_LEVEL so the stale pending state is
> cleared without being replayed. This was observed in pci_endpoint_test
> as two doorbell handler calls when the DMA-variant test ran before
> DOORBELL_TEST.
> 
> Fixes: d9d5e1bdd180 ("dmaengine: dw-edma: Add virtual IRQ for interrupt-emulation doorbells")
> Cc: stable@xxxxxxxxxxxxxxx
> Reported-by: Niklas Cassel <cassel@xxxxxxxxxx>
> Closes: https://lore.kernel.org/r/ampndLtU32ODmncX@ryzen
> Tested-by: Niklas Cassel <cassel@xxxxxxxxxx>
> Signed-off-by: Koichiro Den <den@xxxxxxxxxxxxx>

MSI handling by DWC cores is a mess. Thanks for fixing this issue:

Reviewed-by: Manivannan Sadhasivam <mani@xxxxxxxxxx>

- Mani

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