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

[Koichiro Den]

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>

[+Cc Niklas]

Sorry, I forgot to Cc Niklas.
I relied too much on the get_maintainer.pl (again..)
Niklas, thanks for reporting, discussing and testing.

Best regards,
Koichiro

> ---
>  drivers/dma/dw-edma/dw-edma-core.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
> index 89a4c498a17b..ec097c68cf5f 100644
> --- a/drivers/dma/dw-edma/dw-edma-core.c
> +++ b/drivers/dma/dw-edma/dw-edma-core.c
> @@ -755,6 +755,7 @@ static int dw_edma_emul_irq_alloc(struct dw_edma *dw)
>  		return virq;
>  
>  	irq_set_chip_and_handler(virq, &dw_edma_emul_irqchip, handle_level_irq);
> +	irq_set_status_flags(virq, IRQ_LEVEL);
>  	irq_set_chip_data(virq, dw);
>  	irq_set_noprobe(virq);
>  
> 
> base-commit: f5098b6bae761e346ebcd9da7f95622c04733cff
> -- 
> 2.51.0
>