[PATCH V3] dmaengine: imx-sdma: Fix SPBA bus detection on multi-SPBA platforms

[PATCH V3] dmaengine: imx-sdma: Fix SPBA bus detection on multi-SPBA platforms

[Shengjiu Wang]

i.MX8M platforms have multiple SPBA buses under different AIPS buses.
The current code searches the entire device tree and returns the first
SPBA bus found, which may not be under the same AIPS bus as the SDMA
controller.

This breaks SDMA P2P transfers because the SDMA script needs to know
if peripherals are on SPBA or AIPS to configure watermark levels
correctly. Using the wrong SPBA bus causes DMA timeouts and transfer
failures.

Fix by searching for the SPBA bus under the SDMA's parent node (AIPS)
first, then falling back to a global search for backward compatibility.

Example device tree showing the issue:
  aips1 {
    spba1 { sai@...; };      /* Correct SPBA for sdma1 */
    sdma1@...;
  };
  aips2 {
    spba2 { uart@...; };     /* Wrong SPBA - found first by old code */
  };

Fixes: 8391ecf465ec ("dmaengine: imx-sdma: Add device to device support")
Cc: stable@vger.kernel.org
Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
---
changs in v3:
- add fallback to a global search for backward compatibility, which is
  to address comments from sashiko.dev
- update commit subject and commit message
- add comments in code.
- add Cc stable tag
- Don't add Frank's RB on v2 as there are several other changes.

changes in v2:
- add fixes tag
- use __free(device_node) for auto release. 

 drivers/dma/imx-sdma.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
index 3d527883776b..592705af2319 100644
--- a/drivers/dma/imx-sdma.c
+++ b/drivers/dma/imx-sdma.c
@@ -2364,7 +2364,18 @@ static int sdma_probe(struct platform_device *pdev)
 			return dev_err_probe(&pdev->dev, ret,
 					     "failed to register controller\n");
 
-		spba_bus = of_find_compatible_node(NULL, NULL, "fsl,spba-bus");
+		/*
+		 * On i.MX8M platforms with multiple SPBA buses, we need to find
+		 * the SPBA bus that's under the same AIPS bus as this SDMA controller.
+		 * First check the SDMA's parent (AIPS bus) for a child SPBA bus.
+		 * If not found, fall back to searching the entire device tree for
+		 * backward compatibility with older platforms.
+		 */
+		struct device_node *sdma_parent_np __free(device_node) = of_get_parent(np);
+
+		spba_bus = of_get_compatible_child(sdma_parent_np, "fsl,spba-bus");
+		if (!spba_bus)
+			spba_bus = of_find_compatible_node(NULL, NULL, "fsl,spba-bus");
 		ret = of_address_to_resource(spba_bus, 0, &spba_res);
 		if (!ret) {
 			sdma->spba_start_addr = spba_res.start;
-- 
2.34.1

Re: [PATCH V3] dmaengine: imx-sdma: Fix SPBA bus detection on multi-SPBA platforms

[Frank Li]

On Mon, Apr 20, 2026 at 06:08:54PM +0800, Shengjiu Wang wrote:
> i.MX8M platforms have multiple SPBA buses under different AIPS buses.
> The current code searches the entire device tree and returns the first
> SPBA bus found, which may not be under the same AIPS bus as the SDMA
> controller.
>
> This breaks SDMA P2P transfers because the SDMA script needs to know
> if peripherals are on SPBA or AIPS to configure watermark levels
> correctly. Using the wrong SPBA bus causes DMA timeouts and transfer
> failures.
>
> Fix by searching for the SPBA bus under the SDMA's parent node (AIPS)
> first, then falling back to a global search for backward compatibility.
>
> Example device tree showing the issue:
>   aips1 {
>     spba1 { sai@...; };      /* Correct SPBA for sdma1 */
>     sdma1@...;
>   };
>   aips2 {
>     spba2 { uart@...; };     /* Wrong SPBA - found first by old code */
>   };
>
> Fixes: 8391ecf465ec ("dmaengine: imx-sdma: Add device to device support")
> Cc: stable@vger.kernel.org
> Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
> ---

Reviewed-by: Frank Li <Frank.Li@nxp.com>

> changs in v3:
> - add fallback to a global search for backward compatibility, which is
>   to address comments from sashiko.dev
> - update commit subject and commit message
> - add comments in code.
> - add Cc stable tag
> - Don't add Frank's RB on v2 as there are several other changes.
>
> changes in v2:
> - add fixes tag
> - use __free(device_node) for auto release.
>
>  drivers/dma/imx-sdma.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
> index 3d527883776b..592705af2319 100644
> --- a/drivers/dma/imx-sdma.c
> +++ b/drivers/dma/imx-sdma.c
> @@ -2364,7 +2364,18 @@ static int sdma_probe(struct platform_device *pdev)
>  			return dev_err_probe(&pdev->dev, ret,
>  					     "failed to register controller\n");
>
> -		spba_bus = of_find_compatible_node(NULL, NULL, "fsl,spba-bus");
> +		/*
> +		 * On i.MX8M platforms with multiple SPBA buses, we need to find
> +		 * the SPBA bus that's under the same AIPS bus as this SDMA controller.
> +		 * First check the SDMA's parent (AIPS bus) for a child SPBA bus.
> +		 * If not found, fall back to searching the entire device tree for
> +		 * backward compatibility with older platforms.
> +		 */
> +		struct device_node *sdma_parent_np __free(device_node) = of_get_parent(np);
> +
> +		spba_bus = of_get_compatible_child(sdma_parent_np, "fsl,spba-bus");
> +		if (!spba_bus)
> +			spba_bus = of_find_compatible_node(NULL, NULL, "fsl,spba-bus");
>  		ret = of_address_to_resource(spba_bus, 0, &spba_res);
>  		if (!ret) {
>  			sdma->spba_start_addr = spba_res.start;
> --
> 2.34.1
>

Re: [PATCH V3] dmaengine: imx-sdma: Fix SPBA bus detection on multi-SPBA platforms

[Marco Felsch]

On 26-04-20, Shengjiu Wang wrote:
> i.MX8M platforms have multiple SPBA buses under different AIPS buses.
> The current code searches the entire device tree and returns the first
> SPBA bus found, which may not be under the same AIPS bus as the SDMA
> controller.
> 
> This breaks SDMA P2P transfers because the SDMA script needs to know
> if peripherals are on SPBA or AIPS to configure watermark levels
> correctly. Using the wrong SPBA bus causes DMA timeouts and transfer
> failures.
> 
> Fix by searching for the SPBA bus under the SDMA's parent node (AIPS)
> first, then falling back to a global search for backward compatibility.
> 
> Example device tree showing the issue:
>   aips1 {
>     spba1 { sai@...; };      /* Correct SPBA for sdma1 */
>     sdma1@...;
>   };
>   aips2 {
>     spba2 { uart@...; };     /* Wrong SPBA - found first by old code */
>   };
> 
> Fixes: 8391ecf465ec ("dmaengine: imx-sdma: Add device to device support")
> Cc: stable@vger.kernel.org
> Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
> ---
> changs in v3:
> - add fallback to a global search for backward compatibility, which is
>   to address comments from sashiko.dev
> - update commit subject and commit message
> - add comments in code.
> - add Cc stable tag
> - Don't add Frank's RB on v2 as there are several other changes.
> 
> changes in v2:
> - add fixes tag
> - use __free(device_node) for auto release. 
> 
>  drivers/dma/imx-sdma.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
> index 3d527883776b..592705af2319 100644
> --- a/drivers/dma/imx-sdma.c
> +++ b/drivers/dma/imx-sdma.c
> @@ -2364,7 +2364,18 @@ static int sdma_probe(struct platform_device *pdev)
>  			return dev_err_probe(&pdev->dev, ret,
>  					     "failed to register controller\n");
>  
> -		spba_bus = of_find_compatible_node(NULL, NULL, "fsl,spba-bus");
> +		/*
> +		 * On i.MX8M platforms with multiple SPBA buses, we need to find
> +		 * the SPBA bus that's under the same AIPS bus as this SDMA controller.
> +		 * First check the SDMA's parent (AIPS bus) for a child SPBA bus.
> +		 * If not found, fall back to searching the entire device tree for
> +		 * backward compatibility with older platforms.
> +		 */
> +		struct device_node *sdma_parent_np __free(device_node) = of_get_parent(np);
> +
> +		spba_bus = of_get_compatible_child(sdma_parent_np, "fsl,spba-bus");
> +		if (!spba_bus)
> +			spba_bus = of_find_compatible_node(NULL, NULL, "fsl,spba-bus");

And yet the search is still broken for i.MX8MP case since this platform
has two sdma engines below the bus@30df0000.

Regards,
  Marco

>  		ret = of_address_to_resource(spba_bus, 0, &spba_res);
>  		if (!ret) {
>  			sdma->spba_start_addr = spba_res.start;
> -- 
> 2.34.1
> 
> 
> 

-- 
#gernperDu 
#CallMeByMyFirstName

Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | https://www.pengutronix.de/ |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-9    |

Re: [PATCH V3] dmaengine: imx-sdma: Fix SPBA bus detection on multi-SPBA platforms

[Shengjiu Wang]

On Tue, Apr 21, 2026 at 4:57 PM Marco Felsch <m.felsch@pengutronix.de> wrote:
>
> On 26-04-20, Shengjiu Wang wrote:
> > i.MX8M platforms have multiple SPBA buses under different AIPS buses.
> > The current code searches the entire device tree and returns the first
> > SPBA bus found, which may not be under the same AIPS bus as the SDMA
> > controller.
> >
> > This breaks SDMA P2P transfers because the SDMA script needs to know
> > if peripherals are on SPBA or AIPS to configure watermark levels
> > correctly. Using the wrong SPBA bus causes DMA timeouts and transfer
> > failures.
> >
> > Fix by searching for the SPBA bus under the SDMA's parent node (AIPS)
> > first, then falling back to a global search for backward compatibility.
> >
> > Example device tree showing the issue:
> >   aips1 {
> >     spba1 { sai@...; };      /* Correct SPBA for sdma1 */
> >     sdma1@...;
> >   };
> >   aips2 {
> >     spba2 { uart@...; };     /* Wrong SPBA - found first by old code */
> >   };
> >
> > Fixes: 8391ecf465ec ("dmaengine: imx-sdma: Add device to device support")
> > Cc: stable@vger.kernel.org
> > Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
> > ---
> > changs in v3:
> > - add fallback to a global search for backward compatibility, which is
> >   to address comments from sashiko.dev
> > - update commit subject and commit message
> > - add comments in code.
> > - add Cc stable tag
> > - Don't add Frank's RB on v2 as there are several other changes.
> >
> > changes in v2:
> > - add fixes tag
> > - use __free(device_node) for auto release.
> >
> >  drivers/dma/imx-sdma.c | 13 ++++++++++++-
> >  1 file changed, 12 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
> > index 3d527883776b..592705af2319 100644
> > --- a/drivers/dma/imx-sdma.c
> > +++ b/drivers/dma/imx-sdma.c
> > @@ -2364,7 +2364,18 @@ static int sdma_probe(struct platform_device *pdev)
> >                       return dev_err_probe(&pdev->dev, ret,
> >                                            "failed to register controller\n");
> >
> > -             spba_bus = of_find_compatible_node(NULL, NULL, "fsl,spba-bus");
> > +             /*
> > +              * On i.MX8M platforms with multiple SPBA buses, we need to find
> > +              * the SPBA bus that's under the same AIPS bus as this SDMA controller.
> > +              * First check the SDMA's parent (AIPS bus) for a child SPBA bus.
> > +              * If not found, fall back to searching the entire device tree for
> > +              * backward compatibility with older platforms.
> > +              */
> > +             struct device_node *sdma_parent_np __free(device_node) = of_get_parent(np);
> > +
> > +             spba_bus = of_get_compatible_child(sdma_parent_np, "fsl,spba-bus");
> > +             if (!spba_bus)
> > +                     spba_bus = of_find_compatible_node(NULL, NULL, "fsl,spba-bus");
>
> And yet the search is still broken for i.MX8MP case since this platform
> has two sdma engines below the bus@30df0000.

I tested on i.MX8MP. It works.  Above line is for backward compatibility

The search has no dependence on the number of sdma engines. It searches the
spba-bus, not the sdma node. it will find the aips5 first, then find
the spba-bus for
sdma2 and sdma3.

aips5: bus@30df0000 {
      spba-bus@30c00000 {
       }
       sdma2: dma-controller@30e10000 {
       }
       sdma3: dma-controller@30e00000 {
      }
}

Best regards
Shengjiu Wang

>
> Regards,
>   Marco
>
> >               ret = of_address_to_resource(spba_bus, 0, &spba_res);
> >               if (!ret) {
> >                       sdma->spba_start_addr = spba_res.start;
> > --
> > 2.34.1
> >
> >
> >
>
> --
> #gernperDu
> #CallMeByMyFirstName
>
> Pengutronix e.K.                           |                             |
> Steuerwalder Str. 21                       | https://www.pengutronix.de/ |
> 31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
> Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-9    |
>

Re: [PATCH V3] dmaengine: imx-sdma: Fix SPBA bus detection on multi-SPBA platforms

[Marco Felsch]

On 26-04-21, Shengjiu Wang wrote:
> On Tue, Apr 21, 2026 at 4:57 PM Marco Felsch <m.felsch@pengutronix.de> wrote:
> >
> > On 26-04-20, Shengjiu Wang wrote:
> > > i.MX8M platforms have multiple SPBA buses under different AIPS buses.
> > > The current code searches the entire device tree and returns the first
> > > SPBA bus found, which may not be under the same AIPS bus as the SDMA
> > > controller.
> > >
> > > This breaks SDMA P2P transfers because the SDMA script needs to know
> > > if peripherals are on SPBA or AIPS to configure watermark levels
> > > correctly. Using the wrong SPBA bus causes DMA timeouts and transfer
> > > failures.
> > >
> > > Fix by searching for the SPBA bus under the SDMA's parent node (AIPS)
> > > first, then falling back to a global search for backward compatibility.
> > >
> > > Example device tree showing the issue:
> > >   aips1 {
> > >     spba1 { sai@...; };      /* Correct SPBA for sdma1 */
> > >     sdma1@...;
> > >   };
> > >   aips2 {
> > >     spba2 { uart@...; };     /* Wrong SPBA - found first by old code */
> > >   };
> > >
> > > Fixes: 8391ecf465ec ("dmaengine: imx-sdma: Add device to device support")
> > > Cc: stable@vger.kernel.org
> > > Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
> > > ---
> > > changs in v3:
> > > - add fallback to a global search for backward compatibility, which is
> > >   to address comments from sashiko.dev
> > > - update commit subject and commit message
> > > - add comments in code.
> > > - add Cc stable tag
> > > - Don't add Frank's RB on v2 as there are several other changes.
> > >
> > > changes in v2:
> > > - add fixes tag
> > > - use __free(device_node) for auto release.
> > >
> > >  drivers/dma/imx-sdma.c | 13 ++++++++++++-
> > >  1 file changed, 12 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
> > > index 3d527883776b..592705af2319 100644
> > > --- a/drivers/dma/imx-sdma.c
> > > +++ b/drivers/dma/imx-sdma.c
> > > @@ -2364,7 +2364,18 @@ static int sdma_probe(struct platform_device *pdev)
> > >                       return dev_err_probe(&pdev->dev, ret,
> > >                                            "failed to register controller\n");
> > >
> > > -             spba_bus = of_find_compatible_node(NULL, NULL, "fsl,spba-bus");
> > > +             /*
> > > +              * On i.MX8M platforms with multiple SPBA buses, we need to find
> > > +              * the SPBA bus that's under the same AIPS bus as this SDMA controller.
> > > +              * First check the SDMA's parent (AIPS bus) for a child SPBA bus.
> > > +              * If not found, fall back to searching the entire device tree for
> > > +              * backward compatibility with older platforms.
> > > +              */
> > > +             struct device_node *sdma_parent_np __free(device_node) = of_get_parent(np);
> > > +
> > > +             spba_bus = of_get_compatible_child(sdma_parent_np, "fsl,spba-bus");
> > > +             if (!spba_bus)
> > > +                     spba_bus = of_find_compatible_node(NULL, NULL, "fsl,spba-bus");
> >
> > And yet the search is still broken for i.MX8MP case since this platform
> > has two sdma engines below the bus@30df0000.
> 
> I tested on i.MX8MP. It works.  Above line is for backward compatibility
> 
> The search has no dependence on the number of sdma engines. It searches the
> spba-bus, not the sdma node. it will find the aips5 first, then find
> the spba-bus for
> sdma2 and sdma3.

And you're abosulte certain that NXP doesn't introduce a 2nd SPBA bus
below the same AIPS in which case the driver is broken again?

Sorry for beeing a bit picky. I do see that NXP decided to drop the SDMA
for i.MX9, at least I don't find any reference in which case I'm fine
with the patch.

Regards,
  Marco




> 
> aips5: bus@30df0000 {
>       spba-bus@30c00000 {
>        }
>        sdma2: dma-controller@30e10000 {
>        }
>        sdma3: dma-controller@30e00000 {
>       }
> }
> 
> Best regards
> Shengjiu Wang
> 
> >
> > Regards,
> >   Marco
> >
> > >               ret = of_address_to_resource(spba_bus, 0, &spba_res);
> > >               if (!ret) {
> > >                       sdma->spba_start_addr = spba_res.start;
> > > --
> > > 2.34.1
> > >
> > >
> > >
> >
> > --
> > #gernperDu
> > #CallMeByMyFirstName
> >
> > Pengutronix e.K.                           |                             |
> > Steuerwalder Str. 21                       | https://www.pengutronix.de/ |
> > 31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
> > Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-9    |
> >
> 

-- 
#gernperDu 
#CallMeByMyFirstName

Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | https://www.pengutronix.de/ |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-9    |

Re: [PATCH V3] dmaengine: imx-sdma: Fix SPBA bus detection on multi-SPBA platforms

[Shengjiu Wang]

On Tue, Apr 21, 2026 at 5:44 PM Marco Felsch <m.felsch@pengutronix.de> wrote:
>
> On 26-04-21, Shengjiu Wang wrote:
> > On Tue, Apr 21, 2026 at 4:57 PM Marco Felsch <m.felsch@pengutronix.de> wrote:
> > >
> > > On 26-04-20, Shengjiu Wang wrote:
> > > > i.MX8M platforms have multiple SPBA buses under different AIPS buses.
> > > > The current code searches the entire device tree and returns the first
> > > > SPBA bus found, which may not be under the same AIPS bus as the SDMA
> > > > controller.
> > > >
> > > > This breaks SDMA P2P transfers because the SDMA script needs to know
> > > > if peripherals are on SPBA or AIPS to configure watermark levels
> > > > correctly. Using the wrong SPBA bus causes DMA timeouts and transfer
> > > > failures.
> > > >
> > > > Fix by searching for the SPBA bus under the SDMA's parent node (AIPS)
> > > > first, then falling back to a global search for backward compatibility.
> > > >
> > > > Example device tree showing the issue:
> > > >   aips1 {
> > > >     spba1 { sai@...; };      /* Correct SPBA for sdma1 */
> > > >     sdma1@...;
> > > >   };
> > > >   aips2 {
> > > >     spba2 { uart@...; };     /* Wrong SPBA - found first by old code */
> > > >   };
> > > >
> > > > Fixes: 8391ecf465ec ("dmaengine: imx-sdma: Add device to device support")
> > > > Cc: stable@vger.kernel.org
> > > > Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
> > > > ---
> > > > changs in v3:
> > > > - add fallback to a global search for backward compatibility, which is
> > > >   to address comments from sashiko.dev
> > > > - update commit subject and commit message
> > > > - add comments in code.
> > > > - add Cc stable tag
> > > > - Don't add Frank's RB on v2 as there are several other changes.
> > > >
> > > > changes in v2:
> > > > - add fixes tag
> > > > - use __free(device_node) for auto release.
> > > >
> > > >  drivers/dma/imx-sdma.c | 13 ++++++++++++-
> > > >  1 file changed, 12 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
> > > > index 3d527883776b..592705af2319 100644
> > > > --- a/drivers/dma/imx-sdma.c
> > > > +++ b/drivers/dma/imx-sdma.c
> > > > @@ -2364,7 +2364,18 @@ static int sdma_probe(struct platform_device *pdev)
> > > >                       return dev_err_probe(&pdev->dev, ret,
> > > >                                            "failed to register controller\n");
> > > >
> > > > -             spba_bus = of_find_compatible_node(NULL, NULL, "fsl,spba-bus");
> > > > +             /*
> > > > +              * On i.MX8M platforms with multiple SPBA buses, we need to find
> > > > +              * the SPBA bus that's under the same AIPS bus as this SDMA controller.
> > > > +              * First check the SDMA's parent (AIPS bus) for a child SPBA bus.
> > > > +              * If not found, fall back to searching the entire device tree for
> > > > +              * backward compatibility with older platforms.
> > > > +              */
> > > > +             struct device_node *sdma_parent_np __free(device_node) = of_get_parent(np);
> > > > +
> > > > +             spba_bus = of_get_compatible_child(sdma_parent_np, "fsl,spba-bus");
> > > > +             if (!spba_bus)
> > > > +                     spba_bus = of_find_compatible_node(NULL, NULL, "fsl,spba-bus");
> > >
> > > And yet the search is still broken for i.MX8MP case since this platform
> > > has two sdma engines below the bus@30df0000.
> >
> > I tested on i.MX8MP. It works.  Above line is for backward compatibility
> >
> > The search has no dependence on the number of sdma engines. It searches the
> > spba-bus, not the sdma node. it will find the aips5 first, then find
> > the spba-bus for
> > sdma2 and sdma3.
>
> And you're abosulte certain that NXP doesn't introduce a 2nd SPBA bus
> below the same AIPS in which case the driver is broken again?

Good question. Currently there are no two SPBA buses in the same AIPS
for all existing i.MX platforms and there is no such plan in the
current roadmap,
SDMA is replaced by EDMA from i.MX9.

>
> Sorry for beeing a bit picky. I do see that NXP decided to drop the SDMA
> for i.MX9, at least I don't find any reference in which case I'm fine
> with the patch.

Thanks.  The change should be safe.

Best regards
Shengjiu Wang