[PATCH RESEND] dmaengine: at_xdmac: get the number of DMA channels from device tree

[PATCH RESEND] dmaengine: at_xdmac: get the number of DMA channels from device tree

[Robert Marko]

From: Tony Han <tony.han@microchip.com>

In case of kernel runs in non-secure mode, the number of DMA channels can
be got from device tree since the value read from GTYPE register is "0" as
it's always secured.

As the number of channels can never be negative, update them to the type
"unsigned".

This is required for LAN969x.

Signed-off-by: Tony Han <tony.han@microchip.com>
Signed-off-by: Robert Marko <robert.marko@sartura.hr>
---
 drivers/dma/at_xdmac.c | 26 +++++++++++++++++++++++---
 1 file changed, 23 insertions(+), 3 deletions(-)

diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
index 3fbc74710a13..acabf82e293c 100644
--- a/drivers/dma/at_xdmac.c
+++ b/drivers/dma/at_xdmac.c
@@ -2257,12 +2257,29 @@ static int __maybe_unused atmel_xdmac_runtime_resume(struct device *dev)
 	return clk_enable(atxdmac->clk);
 }
 
+static inline int at_xdmac_get_channel_number(struct platform_device *pdev,
+					      u32 reg, u32 *pchannels)
+{
+	int	ret;
+
+	if (reg) {
+		*pchannels = AT_XDMAC_NB_CH(reg);
+		return 0;
+	}
+
+	ret = of_property_read_u32(pdev->dev.of_node, "dma-channels", pchannels);
+	if (ret)
+		dev_err(&pdev->dev, "can't get number of channels\n");
+
+	return ret;
+}
+
 static int at_xdmac_probe(struct platform_device *pdev)
 {
 	struct at_xdmac	*atxdmac;
-	int		irq, nr_channels, i, ret;
+	int		irq, ret;
 	void __iomem	*base;
-	u32		reg;
+	u32		nr_channels, i, reg;
 
 	irq = platform_get_irq(pdev, 0);
 	if (irq < 0)
@@ -2278,7 +2295,10 @@ static int at_xdmac_probe(struct platform_device *pdev)
 	 * of channels to do the allocation.
 	 */
 	reg = readl_relaxed(base + AT_XDMAC_GTYPE);
-	nr_channels = AT_XDMAC_NB_CH(reg);
+	ret = at_xdmac_get_channel_number(pdev, reg, &nr_channels);
+	if (ret)
+		return ret;
+
 	if (nr_channels > AT_XDMAC_MAX_CHAN) {
 		dev_err(&pdev->dev, "invalid number of channels (%u)\n",
 			nr_channels);
-- 
2.52.0

Re: [PATCH RESEND] dmaengine: at_xdmac: get the number of DMA channels from device tree

[Vinod Koul]

On 03-12-25, 13:11, Robert Marko wrote:
> From: Tony Han <tony.han@microchip.com>
> 
> In case of kernel runs in non-secure mode, the number of DMA channels can
> be got from device tree since the value read from GTYPE register is "0" as
> it's always secured.
> 
> As the number of channels can never be negative, update them to the type
> "unsigned".
> 
> This is required for LAN969x.

You updated the changelog, but tagged it as resend. It should be v2!

> 
> Signed-off-by: Tony Han <tony.han@microchip.com>
> Signed-off-by: Robert Marko <robert.marko@sartura.hr>
> ---
>  drivers/dma/at_xdmac.c | 26 +++++++++++++++++++++++---
>  1 file changed, 23 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
> index 3fbc74710a13..acabf82e293c 100644
> --- a/drivers/dma/at_xdmac.c
> +++ b/drivers/dma/at_xdmac.c
> @@ -2257,12 +2257,29 @@ static int __maybe_unused atmel_xdmac_runtime_resume(struct device *dev)
>  	return clk_enable(atxdmac->clk);
>  }
>  
> +static inline int at_xdmac_get_channel_number(struct platform_device *pdev,
> +					      u32 reg, u32 *pchannels)
> +{
> +	int	ret;
> +
> +	if (reg) {
> +		*pchannels = AT_XDMAC_NB_CH(reg);
> +		return 0;
> +	}
> +
> +	ret = of_property_read_u32(pdev->dev.of_node, "dma-channels", pchannels);
> +	if (ret)
> +		dev_err(&pdev->dev, "can't get number of channels\n");

Do we need to log error, I thought the API did that...

> +
> +	return ret;
> +}
> +
>  static int at_xdmac_probe(struct platform_device *pdev)
>  {
>  	struct at_xdmac	*atxdmac;
> -	int		irq, nr_channels, i, ret;
> +	int		irq, ret;
>  	void __iomem	*base;
> -	u32		reg;
> +	u32		nr_channels, i, reg;
>  
>  	irq = platform_get_irq(pdev, 0);
>  	if (irq < 0)
> @@ -2278,7 +2295,10 @@ static int at_xdmac_probe(struct platform_device *pdev)
>  	 * of channels to do the allocation.
>  	 */
>  	reg = readl_relaxed(base + AT_XDMAC_GTYPE);
> -	nr_channels = AT_XDMAC_NB_CH(reg);
> +	ret = at_xdmac_get_channel_number(pdev, reg, &nr_channels);
> +	if (ret)
> +		return ret;
> +
>  	if (nr_channels > AT_XDMAC_MAX_CHAN) {
>  		dev_err(&pdev->dev, "invalid number of channels (%u)\n",
>  			nr_channels);
> -- 
> 2.52.0

-- 
~Vinod

Re: [PATCH RESEND] dmaengine: at_xdmac: get the number of DMA channels from device tree

[Robert Marko]

On Tue, Dec 16, 2025 at 4:18 PM Vinod Koul <vkoul@kernel.org> wrote:
>
> On 03-12-25, 13:11, Robert Marko wrote:
> > From: Tony Han <tony.han@microchip.com>
> >
> > In case of kernel runs in non-secure mode, the number of DMA channels can
> > be got from device tree since the value read from GTYPE register is "0" as
> > it's always secured.
> >
> > As the number of channels can never be negative, update them to the type
> > "unsigned".
> >
> > This is required for LAN969x.
>
> You updated the changelog, but tagged it as resend. It should be v2!

Hi,
Sorry for this, I sent the wrong patch and though quickly resending
the right one would be better.

>
> >
> > Signed-off-by: Tony Han <tony.han@microchip.com>
> > Signed-off-by: Robert Marko <robert.marko@sartura.hr>
> > ---
> >  drivers/dma/at_xdmac.c | 26 +++++++++++++++++++++++---
> >  1 file changed, 23 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/dma/at_xdmac.c b/drivers/dma/at_xdmac.c
> > index 3fbc74710a13..acabf82e293c 100644
> > --- a/drivers/dma/at_xdmac.c
> > +++ b/drivers/dma/at_xdmac.c
> > @@ -2257,12 +2257,29 @@ static int __maybe_unused atmel_xdmac_runtime_resume(struct device *dev)
> >       return clk_enable(atxdmac->clk);
> >  }
> >
> > +static inline int at_xdmac_get_channel_number(struct platform_device *pdev,
> > +                                           u32 reg, u32 *pchannels)
> > +{
> > +     int     ret;
> > +
> > +     if (reg) {
> > +             *pchannels = AT_XDMAC_NB_CH(reg);
> > +             return 0;
> > +     }
> > +
> > +     ret = of_property_read_u32(pdev->dev.of_node, "dma-channels", pchannels);
> > +     if (ret)
> > +             dev_err(&pdev->dev, "can't get number of channels\n");
>
> Do we need to log error, I thought the API did that...

I dont think API helps here, we would just be left with the error
code, which can be hard
to trace back but I am flexible.

Regards,
Robert
>
> > +
> > +     return ret;
> > +}
> > +
> >  static int at_xdmac_probe(struct platform_device *pdev)
> >  {
> >       struct at_xdmac *atxdmac;
> > -     int             irq, nr_channels, i, ret;
> > +     int             irq, ret;
> >       void __iomem    *base;
> > -     u32             reg;
> > +     u32             nr_channels, i, reg;
> >
> >       irq = platform_get_irq(pdev, 0);
> >       if (irq < 0)
> > @@ -2278,7 +2295,10 @@ static int at_xdmac_probe(struct platform_device *pdev)
> >        * of channels to do the allocation.
> >        */
> >       reg = readl_relaxed(base + AT_XDMAC_GTYPE);
> > -     nr_channels = AT_XDMAC_NB_CH(reg);
> > +     ret = at_xdmac_get_channel_number(pdev, reg, &nr_channels);
> > +     if (ret)
> > +             return ret;
> > +
> >       if (nr_channels > AT_XDMAC_MAX_CHAN) {
> >               dev_err(&pdev->dev, "invalid number of channels (%u)\n",
> >                       nr_channels);
> > --
> > 2.52.0
>
> --
> ~Vinod



-- 
Robert Marko
Staff Embedded Linux Engineer
Sartura d.d.
Lendavska ulica 16a
10000 Zagreb, Croatia
Email: robert.marko@sartura.hr
Web: www.sartura.hr

Re: [PATCH RESEND] dmaengine: at_xdmac: get the number of DMA channels from device tree

[Vinod Koul]

On Wed, 03 Dec 2025 13:11:43 +0100, Robert Marko wrote:
> In case of kernel runs in non-secure mode, the number of DMA channels can
> be got from device tree since the value read from GTYPE register is "0" as
> it's always secured.
> 
> As the number of channels can never be negative, update them to the type
> "unsigned".
> 
> [...]

Applied, thanks!

[1/1] dmaengine: at_xdmac: get the number of DMA channels from device tree
      commit: d3824968dbd9056844bbd5041020a3e28c748558

Best regards,
-- 
~Vinod