[PATCH 0/3] Determine number of DMA channels by 'dma-channels' property

[PATCH 0/3] Determine number of DMA channels by 'dma-channels' property

[Zong Li]

The PDMA driver currently assumes there are four channels by default, it
might cause the error if there is actually less than four channels.
Change that by getting number of channel dynamically from device tree.

This patch set contains the dts and dt-bindings change.

Zong Li (3):
  riscv: dts: Add dma-channels property in dma node
  dt-bindings: Add dma-channels for pdma device node
  dmaengine: sf-pdma: Get number of channel by device tree

 .../bindings/dma/sifive,fu540-c000-pdma.yaml      |  6 ++++++
 arch/riscv/boot/dts/microchip/microchip-mpfs.dtsi |  1 +
 arch/riscv/boot/dts/sifive/fu540-c000.dtsi        |  1 +
 drivers/dma/sf-pdma/sf-pdma.c                     | 15 +++++++++------
 drivers/dma/sf-pdma/sf-pdma.h                     |  8 ++------
 5 files changed, 19 insertions(+), 12 deletions(-)

-- 
2.31.1

[PATCH 0/3] Determine number of DMA channels by 'dma-channels' property

[Zong Li]

The PDMA driver currently assumes there are four channels by default, it
might cause the error if there is actually less than four channels.
Change that by getting number of channel dynamically from device tree.

This patch set contains the dts and dt-bindings change.

Zong Li (3):
  riscv: dts: Add dma-channels property in dma node
  dt-bindings: Add dma-channels for pdma device node
  dmaengine: sf-pdma: Get number of channel by device tree

 .../bindings/dma/sifive,fu540-c000-pdma.yaml      |  6 ++++++
 arch/riscv/boot/dts/microchip/microchip-mpfs.dtsi |  1 +
 arch/riscv/boot/dts/sifive/fu540-c000.dtsi        |  1 +
 drivers/dma/sf-pdma/sf-pdma.c                     | 15 +++++++++------
 drivers/dma/sf-pdma/sf-pdma.h                     |  8 ++------
 5 files changed, 19 insertions(+), 12 deletions(-)

-- 
2.31.1

[PATCH 1/3] riscv: dts: Add dma-channels property in dma node

[Zong Li]

Add dma-channels property, then we can determine how many channels there
by device tree.

Signed-off-by: Zong Li <zong.li@sifive.com>
---
 arch/riscv/boot/dts/microchip/microchip-mpfs.dtsi | 1 +
 arch/riscv/boot/dts/sifive/fu540-c000.dtsi        | 1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/riscv/boot/dts/microchip/microchip-mpfs.dtsi b/arch/riscv/boot/dts/microchip/microchip-mpfs.dtsi
index c9f6d205d2ba..3c48f2d7a4a4 100644
--- a/arch/riscv/boot/dts/microchip/microchip-mpfs.dtsi
+++ b/arch/riscv/boot/dts/microchip/microchip-mpfs.dtsi
@@ -188,6 +188,7 @@ dma@3000000 {
 			reg = <0x0 0x3000000 0x0 0x8000>;
 			interrupt-parent = <&plic>;
 			interrupts = <23 24 25 26 27 28 29 30>;
+			dma-channels = <4>;
 			#dma-cells = <1>;
 		};
 
diff --git a/arch/riscv/boot/dts/sifive/fu540-c000.dtsi b/arch/riscv/boot/dts/sifive/fu540-c000.dtsi
index 0655b5c4201d..2bdfe7f06e4b 100644
--- a/arch/riscv/boot/dts/sifive/fu540-c000.dtsi
+++ b/arch/riscv/boot/dts/sifive/fu540-c000.dtsi
@@ -171,6 +171,7 @@ dma: dma@3000000 {
 			reg = <0x0 0x3000000 0x0 0x8000>;
 			interrupt-parent = <&plic0>;
 			interrupts = <23 24 25 26 27 28 29 30>;
+			dma-channels = <4>;
 			#dma-cells = <1>;
 		};
 		uart1: serial@10011000 {
-- 
2.31.1

[PATCH 2/3] dt-bindings: Add dma-channels for pdma device node

[Zong Li]

Add dma-channels property, then we can determine how many channels there
by device tree, rather than statically defines it in PDMA driver

Signed-off-by: Zong Li <zong.li@sifive.com>
---
 .../devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml     | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml b/Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml
index d32a71b975fe..256bcb111d57 100644
--- a/Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml
+++ b/Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml
@@ -34,12 +34,17 @@ properties:
     minItems: 1
     maxItems: 8
 
+  dma-channels:
+    minimum: 1
+    maximum: 4
+
   '#dma-cells':
     const: 1
 
 required:
   - compatible
   - reg
+  - dma-channels
   - interrupts
   - '#dma-cells'
 
@@ -50,6 +55,7 @@ examples:
     dma@3000000 {
       compatible = "sifive,fu540-c000-pdma";
       reg = <0x3000000 0x8000>;
+      dma-channels = <4>;
       interrupts = <23 24 25 26 27 28 29 30>;
       #dma-cells = <1>;
     };
-- 
2.31.1

Re: [PATCH 2/3] dt-bindings: Add dma-channels for pdma device node

[Geert Uytterhoeven]

Hi Zong,

On Wed, Jan 5, 2022 at 6:44 AM Zong Li <zong.li@sifive.com> wrote:
> Add dma-channels property, then we can determine how many channels there
> by device tree, rather than statically defines it in PDMA driver
>
> Signed-off-by: Zong Li <zong.li@sifive.com>

Thanks for your patch!

> --- a/Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml
> +++ b/Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml
> @@ -34,12 +34,17 @@ properties:
>      minItems: 1
>      maxItems: 8
>
> +  dma-channels:
> +    minimum: 1
> +    maximum: 4

As per my comment on [PATCH 3/3], perhaps you want to use a default
value of 4, and document that here, too?

> +
>    '#dma-cells':
>      const: 1
>
>  required:
>    - compatible
>    - reg
> +  - dma-channels
>    - interrupts
>    - '#dma-cells'
>


Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH 2/3] dt-bindings: Add dma-channels for pdma device node

[Zong Li]

On Mon, Jan 10, 2022 at 5:00 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>
> Hi Zong,
>
> On Wed, Jan 5, 2022 at 6:44 AM Zong Li <zong.li@sifive.com> wrote:
> > Add dma-channels property, then we can determine how many channels there
> > by device tree, rather than statically defines it in PDMA driver
> >
> > Signed-off-by: Zong Li <zong.li@sifive.com>
>
> Thanks for your patch!
>
> > --- a/Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml
> > +++ b/Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml
> > @@ -34,12 +34,17 @@ properties:
> >      minItems: 1
> >      maxItems: 8
> >
> > +  dma-channels:
> > +    minimum: 1
> > +    maximum: 4
>
> As per my comment on [PATCH 3/3], perhaps you want to use a default
> value of 4, and document that here, too?
>

Thanks for your reminder, it should be modified as well. I would
change it and add a description in the next version.

> > +
> >    '#dma-cells':
> >      const: 1
> >
> >  required:
> >    - compatible
> >    - reg
> > +  - dma-channels
> >    - interrupts
> >    - '#dma-cells'
> >
>
>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds

[PATCH 3/3] dmaengine: sf-pdma: Get number of channel by device tree

[Zong Li]

It currently assumes that there are four channels by default, it might
cause the error if there is actually less than four channels. Change
that by getting number of channel from device tree.

Signed-off-by: Zong Li <zong.li@sifive.com>
---
 drivers/dma/sf-pdma/sf-pdma.c | 15 +++++++++------
 drivers/dma/sf-pdma/sf-pdma.h |  8 ++------
 2 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/drivers/dma/sf-pdma/sf-pdma.c b/drivers/dma/sf-pdma/sf-pdma.c
index f12606aeff87..c941150fc830 100644
--- a/drivers/dma/sf-pdma/sf-pdma.c
+++ b/drivers/dma/sf-pdma/sf-pdma.c
@@ -484,21 +484,24 @@ static int sf_pdma_probe(struct platform_device *pdev)
 	struct sf_pdma *pdma;
 	struct sf_pdma_chan *chan;
 	struct resource *res;
-	int len, chans;
-	int ret;
+	int len, ret;
 	const enum dma_slave_buswidth widths =
 		DMA_SLAVE_BUSWIDTH_1_BYTE | DMA_SLAVE_BUSWIDTH_2_BYTES |
 		DMA_SLAVE_BUSWIDTH_4_BYTES | DMA_SLAVE_BUSWIDTH_8_BYTES |
 		DMA_SLAVE_BUSWIDTH_16_BYTES | DMA_SLAVE_BUSWIDTH_32_BYTES |
 		DMA_SLAVE_BUSWIDTH_64_BYTES;
 
-	chans = PDMA_NR_CH;
-	len = sizeof(*pdma) + sizeof(*chan) * chans;
+	len = sizeof(*pdma) + sizeof(*chan) * PDMA_MAX_NR_CH;
 	pdma = devm_kzalloc(&pdev->dev, len, GFP_KERNEL);
 	if (!pdma)
 		return -ENOMEM;
 
-	pdma->n_chans = chans;
+	ret = of_property_read_u32(pdev->dev.of_node, "dma-channels",
+				   &pdma->n_chans);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to read dma-channels\n");
+		return ret;
+	}
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	pdma->membase = devm_ioremap_resource(&pdev->dev, res);
@@ -556,7 +559,7 @@ static int sf_pdma_remove(struct platform_device *pdev)
 	struct sf_pdma_chan *ch;
 	int i;
 
-	for (i = 0; i < PDMA_NR_CH; i++) {
+	for (i = 0; i < pdma->n_chans; i++) {
 		ch = &pdma->chans[i];
 
 		devm_free_irq(&pdev->dev, ch->txirq, ch);
diff --git a/drivers/dma/sf-pdma/sf-pdma.h b/drivers/dma/sf-pdma/sf-pdma.h
index 0c20167b097d..8127d792f639 100644
--- a/drivers/dma/sf-pdma/sf-pdma.h
+++ b/drivers/dma/sf-pdma/sf-pdma.h
@@ -22,11 +22,7 @@
 #include "../dmaengine.h"
 #include "../virt-dma.h"
 
-#define PDMA_NR_CH					4
-
-#if (PDMA_NR_CH != 4)
-#error "Please define PDMA_NR_CH to 4"
-#endif
+#define PDMA_MAX_NR_CH					4
 
 #define PDMA_BASE_ADDR					0x3000000
 #define PDMA_CHAN_OFFSET				0x1000
@@ -118,7 +114,7 @@ struct sf_pdma {
 	void __iomem            *membase;
 	void __iomem            *mappedbase;
 	u32			n_chans;
-	struct sf_pdma_chan	chans[PDMA_NR_CH];
+	struct sf_pdma_chan	chans[PDMA_MAX_NR_CH];
 };
 
 #endif /* _SF_PDMA_H */
-- 
2.31.1

Re: [PATCH 3/3] dmaengine: sf-pdma: Get number of channel by device tree

[Geert Uytterhoeven]

Hi Zong,

On Wed, Jan 5, 2022 at 6:44 AM Zong Li <zong.li@sifive.com> wrote:
> It currently assumes that there are four channels by default, it might
> cause the error if there is actually less than four channels. Change
> that by getting number of channel from device tree.
>
> Signed-off-by: Zong Li <zong.li@sifive.com>

Thanks for your patch!

> --- a/drivers/dma/sf-pdma/sf-pdma.c
> +++ b/drivers/dma/sf-pdma/sf-pdma.c
> @@ -484,21 +484,24 @@ static int sf_pdma_probe(struct platform_device *pdev)
>         struct sf_pdma *pdma;
>         struct sf_pdma_chan *chan;
>         struct resource *res;
> -       int len, chans;
> -       int ret;
> +       int len, ret;
>         const enum dma_slave_buswidth widths =
>                 DMA_SLAVE_BUSWIDTH_1_BYTE | DMA_SLAVE_BUSWIDTH_2_BYTES |
>                 DMA_SLAVE_BUSWIDTH_4_BYTES | DMA_SLAVE_BUSWIDTH_8_BYTES |
>                 DMA_SLAVE_BUSWIDTH_16_BYTES | DMA_SLAVE_BUSWIDTH_32_BYTES |
>                 DMA_SLAVE_BUSWIDTH_64_BYTES;
>
> -       chans = PDMA_NR_CH;
> -       len = sizeof(*pdma) + sizeof(*chan) * chans;
> +       len = sizeof(*pdma) + sizeof(*chan) * PDMA_MAX_NR_CH;
>         pdma = devm_kzalloc(&pdev->dev, len, GFP_KERNEL);
>         if (!pdma)
>                 return -ENOMEM;
>
> -       pdma->n_chans = chans;
> +       ret = of_property_read_u32(pdev->dev.of_node, "dma-channels",
> +                                  &pdma->n_chans);
> +       if (ret) {
> +               dev_err(&pdev->dev, "failed to read dma-channels\n");
> +               return ret;

Note that this is not backwards-compatible with existing DTBs, which
lack the "dma-channels" property.
Perhaps you want to fallback to a default of 4 instead?

> +       }
>
>         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>         pdma->membase = devm_ioremap_resource(&pdev->dev, res);

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH 3/3] dmaengine: sf-pdma: Get number of channel by device tree

[Zong Li]

On Mon, Jan 10, 2022 at 4:58 PM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
>
> Hi Zong,
>
> On Wed, Jan 5, 2022 at 6:44 AM Zong Li <zong.li@sifive.com> wrote:
> > It currently assumes that there are four channels by default, it might
> > cause the error if there is actually less than four channels. Change
> > that by getting number of channel from device tree.
> >
> > Signed-off-by: Zong Li <zong.li@sifive.com>
>
> Thanks for your patch!
>
> > --- a/drivers/dma/sf-pdma/sf-pdma.c
> > +++ b/drivers/dma/sf-pdma/sf-pdma.c
> > @@ -484,21 +484,24 @@ static int sf_pdma_probe(struct platform_device *pdev)
> >         struct sf_pdma *pdma;
> >         struct sf_pdma_chan *chan;
> >         struct resource *res;
> > -       int len, chans;
> > -       int ret;
> > +       int len, ret;
> >         const enum dma_slave_buswidth widths =
> >                 DMA_SLAVE_BUSWIDTH_1_BYTE | DMA_SLAVE_BUSWIDTH_2_BYTES |
> >                 DMA_SLAVE_BUSWIDTH_4_BYTES | DMA_SLAVE_BUSWIDTH_8_BYTES |
> >                 DMA_SLAVE_BUSWIDTH_16_BYTES | DMA_SLAVE_BUSWIDTH_32_BYTES |
> >                 DMA_SLAVE_BUSWIDTH_64_BYTES;
> >
> > -       chans = PDMA_NR_CH;
> > -       len = sizeof(*pdma) + sizeof(*chan) * chans;
> > +       len = sizeof(*pdma) + sizeof(*chan) * PDMA_MAX_NR_CH;
> >         pdma = devm_kzalloc(&pdev->dev, len, GFP_KERNEL);
> >         if (!pdma)
> >                 return -ENOMEM;
> >
> > -       pdma->n_chans = chans;
> > +       ret = of_property_read_u32(pdev->dev.of_node, "dma-channels",
> > +                                  &pdma->n_chans);
> > +       if (ret) {
> > +               dev_err(&pdev->dev, "failed to read dma-channels\n");
> > +               return ret;
>
> Note that this is not backwards-compatible with existing DTBs, which
> lack the "dma-channels" property.
> Perhaps you want to fallback to a default of 4 instead?
>

Thanks for your advice. I would set n_chans to 4 in failure condition
for backwards-compatible.

> > +       }
> >
> >         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> >         pdma->membase = devm_ioremap_resource(&pdev->dev, res);
>
> Gr{oetje,eeting}s,
>
>                         Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                 -- Linus Torvalds