Re: [PATCH RESEND] dmaengine: qcom: bam_dma: Defer IRQ trigger type to device tree

[Frank Li <Frank.li@oss.nxp.com>]

On Mon, Sep 28, 2026 at 02:38:14PM +0530, Vishnu Santhosh wrote:
> Hi Frank,
>
> On 16-09-2026 08:30 pm, Vishnu Santhosh wrote:
> >
> > On 15-09-2026 07:36 pm, Frank Li wrote:
> > > On Fri, Jul 17, 2026 at 10:30:28AM +0530, Vishnu Santhosh wrote:
> > > > The driver hardcodes IRQF_TRIGGER_HIGH when registering the BAM
> > > > interrupt, which overrides the trigger type specified in the device
> > > > tree. On Qualcomm Shikra SoC, the A2 BAM signals an edge interrupt
> > > > to the apps processor; registering it as level-high causes the
> > > > interrupt to not fire, resulting in missed DMA completions.
> > > >
> > > > Use IRQF_TRIGGER_NONE instead, which causes the kernel to use the
> > > > trigger type already configured by platform_get_irq() when it parsed
> > > > the device tree interrupts property. This makes the driver
> > > > platform-agnostic.
> > > where show this? can you point me doc or code?
> > >
> > > Frank
> >
> > Hi Frank,
> >
> > The BAM driver obtains the IRQ through platform_get_irq():
> >
> > bdev->irq = platform_get_irq(pdev, 0);
> >
> > in https://elixir.bootlin.com/linux/v7.3-rc3/source/drivers/dma/qcom/bam_dma.c#L1270
> >
> > It then registers the same IRQ with:
> >
> > ret = devm_request_irq(bdev->dev, bdev->irq, bam_dma_irq,
> >                          IRQF_TRIGGER_HIGH, "bam_dma", bdev);
> >
> > in https://elixir.bootlin.com/linux/v7.3-rc3/source/drivers/dma/qcom/bam_dma.c#L1335
> >
> > The comment above IRQF_TRIGGER_NONE in include/linux/interrupt.h
> > states that when no trigger flag is specified, the interrupt uses the
> > trigger type already
> > configured by the machine or firmware.
> >
> > https://elixir.bootlin.com/linux/v7.3-rc3/source/include/linux/interrupt.h#L25

Thank you provide it. Kernel doc or comments may miss match actually code
Do you know where exactly handle IRQF_TRIGGER_NONE as what doc said?

Frank

> >
> >
> > Therefore, IRQF_TRIGGER_HIGH overrides the trigger type associated with
> > the IRQ during
> > DT/IRQ-domain mapping, while IRQF_TRIGGER_NONE preserves it.
> >
> > The Shikra DTS which is still under review describes the BAM interrupt
> > as edge-triggered:
> >
> > interrupts = <GIC_SPI 74 IRQ_TYPE_EDGE_RISING 0>;
> >
> > This driver change is needed so that the DT-specified trigger type
> > remains effective once
> > the Shikra DTS change is accepted.
> >
> >
> > Thanks,
> > Vishnu
> >
> Gentle ping on this patch. Please let me know if any other information to be shared
> from my side.
>
>
> Thanks,
> Vishnu
>
> >
> > >
> > > > Fixes: e7c0fe2a5c84 ("dmaengine: add Qualcomm BAM dma driver")
> > > > Co-developed-by: Deepak Kumar Singh <deepak.singh@oss.qualcomm.com>
> > > > Signed-off-by: Deepak Kumar Singh <deepak.singh@oss.qualcomm.com>
> > > > Signed-off-by: Vishnu Santhosh <vishnu.santhosh@oss.qualcomm.com>
> > > > ---
> > > >   drivers/dma/qcom/bam_dma.c | 2 +-
> > > >   1 file changed, 1 insertion(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/dma/qcom/bam_dma.c b/drivers/dma/qcom/bam_dma.c
> > > > index 19116295f8325767a0d97a7848077885b118241c..6c3e2ca8a572fd04c925de0adbd5cc0616b361ef
> > > > 100644
> > > > --- a/drivers/dma/qcom/bam_dma.c
> > > > +++ b/drivers/dma/qcom/bam_dma.c
> > > > @@ -1303,7 +1303,7 @@ static int bam_dma_probe(struct
> > > > platform_device *pdev)
> > > >           bam_channel_init(bdev, &bdev->channels[i], i);
> > > >
> > > >       ret = devm_request_irq(bdev->dev, bdev->irq, bam_dma_irq,
> > > > -            IRQF_TRIGGER_HIGH, "bam_dma", bdev);
> > > > +            IRQF_TRIGGER_NONE, "bam_dma", bdev);
> > > >       if (ret)
> > > >           goto err_bam_channel_exit;
> > > >
> > > >
> > > > ---
> > > > base-commit: e43ffb69e0438cddd72aaa30898b4dc446f664f8
> > > > change-id: 20260601-qcom-bam-dma-irq-trigger-0366e7e86f17
> > > >
> > > > Best regards,
> > > > --
> > > > Vishnu Santhosh <vishnu.santhosh@oss.qualcomm.com>
> > > >