[PATCH] spi: lpspi: disable lpspi module irq in DMA mode

[PATCH] spi: lpspi: disable lpspi module irq in DMA mode

[Clark Wang]

When all bits of IER are set to 0, we still can observe the lpspi irq events
when using DMA mode to transfer data.

So disable irq to avoid the too much irq events.

Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
---
 drivers/spi/spi-fsl-lpspi.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-fsl-lpspi.c b/drivers/spi/spi-fsl-lpspi.c
index f2341ab99556..4b70038ceb6b 100644
--- a/drivers/spi/spi-fsl-lpspi.c
+++ b/drivers/spi/spi-fsl-lpspi.c
@@ -910,9 +910,14 @@ static int fsl_lpspi_probe(struct platform_device *pdev)
 	ret = fsl_lpspi_dma_init(&pdev->dev, fsl_lpspi, controller);
 	if (ret == -EPROBE_DEFER)
 		goto out_pm_get;
-
 	if (ret < 0)
 		dev_err(&pdev->dev, "dma setup error %d, use pio\n", ret);
+	else
+		/*
+		 * disable LPSPI module IRQ when enable DMA mode successfully,
+		 * to prevent the unexpected LPSPI module IRQ events.
+		 */
+		disable_irq(irq);
 
 	ret = devm_spi_register_controller(&pdev->dev, controller);
 	if (ret < 0) {
-- 
2.34.1

Re: [PATCH] spi: lpspi: disable lpspi module irq in DMA mode

[Dhruva Gole]

On 05/05/23 12:05, Clark Wang wrote:
> When all bits of IER are set to 0, we still can observe the lpspi irq events
> when using DMA mode to transfer data.
> 
> So disable irq to avoid the too much irq events.
> 
> Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
> ---
>   drivers/spi/spi-fsl-lpspi.c | 7 ++++++-
>   1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/spi/spi-fsl-lpspi.c b/drivers/spi/spi-fsl-lpspi.c
> index f2341ab99556..4b70038ceb6b 100644
> --- a/drivers/spi/spi-fsl-lpspi.c
> +++ b/drivers/spi/spi-fsl-lpspi.c
> @@ -910,9 +910,14 @@ static int fsl_lpspi_probe(struct platform_device *pdev)
>   	ret = fsl_lpspi_dma_init(&pdev->dev, fsl_lpspi, controller);
>   	if (ret == -EPROBE_DEFER)
>   		goto out_pm_get;
> -

Any reason to delete this line?

>   	if (ret < 0)
>   		dev_err(&pdev->dev, "dma setup error %d, use pio\n", ret);
> +	else
> +		/*
> +		 * disable LPSPI module IRQ when enable DMA mode successfully,
> +		 * to prevent the unexpected LPSPI module IRQ events.
> +		 */
> +		disable_irq(irq);

Just wondering, have you actually seen any unexpected LPSPI module IRQ
events? If this was causing issues earlier then maybe add a fixes tag?

>   
>   	ret = devm_spi_register_controller(&pdev->dev, controller);
>   	if (ret < 0) {

-- 
Thanks and Regards,
Dhruva Gole

RE: [PATCH] spi: lpspi: disable lpspi module irq in DMA mode

[Clark Wang]

Hi Dhruva,

> -----Original Message-----
> From: Dhruva Gole <d-gole@ti.com>
> Sent: 2023年5月5日 17:16
> To: Clark Wang <xiaoning.wang@nxp.com>; broonie@kernel.org
> Cc: linux-spi@vger.kernel.org; linux-kernel@vger.kernel.org
> Subject: Re: [PATCH] spi: lpspi: disable lpspi module irq in DMA mode
> 
> 
> 
> On 05/05/23 12:05, Clark Wang wrote:
> > When all bits of IER are set to 0, we still can observe the lpspi irq
> > events when using DMA mode to transfer data.
> >
> > So disable irq to avoid the too much irq events.
> >
> > Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
> > ---
> >   drivers/spi/spi-fsl-lpspi.c | 7 ++++++-
> >   1 file changed, 6 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/spi/spi-fsl-lpspi.c b/drivers/spi/spi-fsl-lpspi.c
> > index f2341ab99556..4b70038ceb6b 100644
> > --- a/drivers/spi/spi-fsl-lpspi.c
> > +++ b/drivers/spi/spi-fsl-lpspi.c
> > @@ -910,9 +910,14 @@ static int fsl_lpspi_probe(struct platform_device
> *pdev)
> >   	ret = fsl_lpspi_dma_init(&pdev->dev, fsl_lpspi, controller);
> >   	if (ret == -EPROBE_DEFER)
> >   		goto out_pm_get;
> > -
> 
> Any reason to delete this line?

Both of the if statements are used to determine the return value of fsl_lpspi_dma_init(), so I remove this line.

> 
> >   	if (ret < 0)
> >   		dev_err(&pdev->dev, "dma setup error %d, use pio\n", ret);
> > +	else
> > +		/*
> > +		 * disable LPSPI module IRQ when enable DMA mode successfully,
> > +		 * to prevent the unexpected LPSPI module IRQ events.
> > +		 */
> > +		disable_irq(irq);
> 
> Just wondering, have you actually seen any unexpected LPSPI module IRQ
> events? If this was causing issues earlier then maybe add a fixes tag?

Yes, I have observed this issue. 
The reason for this problem is that some older platforms are designed to combine LPSPI interrupt and LPSPI DMA channel interrupt into one shared interrupt number because the IRQ interrupt number is not enough.
When the problem occurs, we can observe that if the interrupt comes too many times and too quickly, it will trigger the IRQ in the LPSPI driver while DMA is still processing the previous DMA request(through the shared dma channel interrupt), resulting in data messing.

Best Regards,
Clark Wang
> 
> >
> >   	ret = devm_spi_register_controller(&pdev->dev, controller);
> >   	if (ret < 0) {
> 
> --
> Thanks and Regards,
> Dhruva Gole

Re: [PATCH] spi: lpspi: disable lpspi module irq in DMA mode

[Mark Brown]

On Fri, 05 May 2023 14:35:57 +0800, Clark Wang wrote:
> When all bits of IER are set to 0, we still can observe the lpspi irq events
> when using DMA mode to transfer data.
> 
> So disable irq to avoid the too much irq events.
> 
> 

Applied to

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/spi.git for-next

Thanks!

[1/1] spi: lpspi: disable lpspi module irq in DMA mode
      commit: 9728fb3ce11729aa8c276825ddf504edeb00611d

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark