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Determine number of DMA channels by 'dma-channels' property

PATCH Superseded Zong Li 2 participants 8 messages Jan 5, 2022 – Jan 11, 2022

Subsystems (6)
Device tree bindings RISC-V dmaengine SiFive drivers +2 more subsystems

v1 of 8 Superseded Latest is v8 →

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Zong Li

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#0 lore raw

cover Determine number of DMA channels by 'dma-channels' property

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(-)
Signature · 1 line
2.31.1
author
#1 lore raw

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

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

Signed-off-by Zong Li <[email protected]>
---
 arch/riscv/boot/dts/microchip/microchip-mpfs.dtsi | 1 +
 arch/riscv/boot/dts/sifive/fu540-c000.dtsi        | 1 +
 2 files changed, 2 insertions(+)
arch/riscv/boot/dts/microchip/microchip-mpfs.dtsi +1 -0
index c9f6d205d2ba..3c48f2d7a4a4 100644
@@ -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>;
 		};
arch/riscv/boot/dts/sifive/fu540-c000.dtsi +1 -0
index 0655b5c4201d..2bdfe7f06e4b 100644
@@ -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 {
Signature · 1 line
2.31.1
author
#2 lore raw

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

In reply to 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 <[email protected]>
---
 .../devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml     | 6 ++++++
 1 file changed, 6 insertions(+)
Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml +6 -0
index d32a71b975fe..256bcb111d57 100644
@@ -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>;
     };
Signature · 1 line
2.31.1
#3 lore raw

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

Hi Zong,

Quoted 4 lines · 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 <[email protected]>

Thanks for your patch!

Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml properties: · line 39

Quoted 9 lines
Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml +3 -0
@@ -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?

Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml properties: · line 50

Quoted 11 lines
Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml +2 -0
+
   '#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 -- [email protected]

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

author
#4 lore raw

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

Quoted 17 lines · Geert Uytterhoeven

Hi Zong,

Quoted 4 lines · 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 <[email protected]>

Thanks for your patch!

Quoted 6 lines
Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml +0 -0
@@ -34,12 +34,17 @@ properties:
     minItems: 1
     maxItems: 8
Quoted 7 lines

Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml properties: · line 39

Quoted 3 lines
Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml +3 -0
+  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.

Quoted 15 lines

Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml properties: · line 50

Quoted 11 lines
Documentation/devicetree/bindings/dma/sifive,fu540-c000-pdma.yaml +2 -0
+
   '#dma-cells':
     const: 1
 
 required:
   - compatible
   - reg
+  - dma-channels
   - interrupts
   - '#dma-cells'

Gr{oetje,eeting}s,

Quoted 8 lines

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]

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

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linux-riscv mailing list
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http://lists.infradead.org/mailman/listinfo/linux-riscv

author
#5 lore raw

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

In reply to 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 <[email protected]>
---
 drivers/dma/sf-pdma/sf-pdma.c | 15 +++++++++------
 drivers/dma/sf-pdma/sf-pdma.h |  8 ++------
 2 files changed, 11 insertions(+), 12 deletions(-)
drivers/dma/sf-pdma/sf-pdma.c +9 -6
index f12606aeff87..c941150fc830 100644
@@ -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);
drivers/dma/sf-pdma/sf-pdma.h +2 -6
index 0c20167b097d..8127d792f639 100644
@@ -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 */
Signature · 1 line
2.31.1
#6 lore raw

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

Hi Zong,

Quoted 5 lines · 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 <[email protected]>

Thanks for your patch!

Quoted 18 lines
drivers/dma/sf-pdma/sf-pdma.c +2 -4
@@ -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;

drivers/dma/sf-pdma/sf-pdma.c static int sf_pdma_probe(struct platform_device *pdev) · line 503

Quoted 10 lines
drivers/dma/sf-pdma/sf-pdma.c +5 -1
        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?

drivers/dma/sf-pdma/sf-pdma.c static int sf_pdma_probe(struct platform_device *pdev) · line 507

Quoted 4 lines
drivers/dma/sf-pdma/sf-pdma.c +1 -0
+       }
 
        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 -- [email protected]

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

author
#7 lore raw

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

Quoted 34 lines · Geert Uytterhoeven

Hi Zong,

Quoted 5 lines · 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 <[email protected]>

Thanks for your patch!

Quoted 22 lines
drivers/dma/sf-pdma/sf-pdma.c +2 -4
@@ -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;
Quoted 11 lines

drivers/dma/sf-pdma/sf-pdma.c static int sf_pdma_probe(struct platform_device *pdev) · line 503

Quoted 6 lines
drivers/dma/sf-pdma/sf-pdma.c +5 -1
-       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.

Quoted 15 lines

drivers/dma/sf-pdma/sf-pdma.c static int sf_pdma_probe(struct platform_device *pdev) · line 507

Quoted 4 lines
drivers/dma/sf-pdma/sf-pdma.c +1 -0
+       }
 
        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 -- [email protected]

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