[PATCH v2] arm64: dts: rockchip: Add dma-names to RK356x UART nodes

[PATCH v2] arm64: dts: rockchip: Add dma-names to RK356x UART nodes

[Jun Yan]

The RK356x UART nodes define a dmas property but omit the matching
dma-names property, so the 8250 driver fails to request a DMA channel
and falls back to PIO, logging:

  of_dma_request_slave_channel: dma-names property of node
  '/serial@fe650000' missing or empty

Add the missing dma-names = "tx", "rx" to uart0 through uart9,
matching other Rockchip SoCs such as the RK3588.

Fixes: a3adc0b9071d ("arm64: dts: rockchip: add core dtsi for RK3568 SoC")
Signed-off-by: Jun Yan <jerrysteve1101@gmail.com>
---
Changes in v2:
  - Add Fixes tag for the commit that introduced the dmas property.

v1: https://lore.kernel.org/all/20261008153620.238580-1-jerrysteve1101@gmail.com/

 arch/arm64/boot/dts/rockchip/rk356x-base.dtsi | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/arch/arm64/boot/dts/rockchip/rk356x-base.dtsi b/arch/arm64/boot/dts/rockchip/rk356x-base.dtsi
index a5832895bd39..098493c04ecc 100644
--- a/arch/arm64/boot/dts/rockchip/rk356x-base.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk356x-base.dtsi
@@ -443,6 +443,7 @@ uart0: serial@fdd50000 {
 		clocks = <&pmucru SCLK_UART0>, <&pmucru PCLK_UART0>;
 		clock-names = "baudclk", "apb_pclk";
 		dmas = <&dmac0 0>, <&dmac0 1>;
+		dma-names = "tx", "rx";
 		pinctrl-0 = <&uart0_xfer>;
 		pinctrl-names = "default";
 		reg-io-width = <4>;
@@ -1449,6 +1450,7 @@ uart1: serial@fe650000 {
 		clocks = <&cru SCLK_UART1>, <&cru PCLK_UART1>;
 		clock-names = "baudclk", "apb_pclk";
 		dmas = <&dmac0 2>, <&dmac0 3>;
+		dma-names = "tx", "rx";
 		pinctrl-0 = <&uart1m0_xfer>;
 		pinctrl-names = "default";
 		reg-io-width = <4>;
@@ -1463,6 +1465,7 @@ uart2: serial@fe660000 {
 		clocks = <&cru SCLK_UART2>, <&cru PCLK_UART2>;
 		clock-names = "baudclk", "apb_pclk";
 		dmas = <&dmac0 4>, <&dmac0 5>;
+		dma-names = "tx", "rx";
 		pinctrl-0 = <&uart2m0_xfer>;
 		pinctrl-names = "default";
 		reg-io-width = <4>;
@@ -1477,6 +1480,7 @@ uart3: serial@fe670000 {
 		clocks = <&cru SCLK_UART3>, <&cru PCLK_UART3>;
 		clock-names = "baudclk", "apb_pclk";
 		dmas = <&dmac0 6>, <&dmac0 7>;
+		dma-names = "tx", "rx";
 		pinctrl-0 = <&uart3m0_xfer>;
 		pinctrl-names = "default";
 		reg-io-width = <4>;
@@ -1491,6 +1495,7 @@ uart4: serial@fe680000 {
 		clocks = <&cru SCLK_UART4>, <&cru PCLK_UART4>;
 		clock-names = "baudclk", "apb_pclk";
 		dmas = <&dmac0 8>, <&dmac0 9>;
+		dma-names = "tx", "rx";
 		pinctrl-0 = <&uart4m0_xfer>;
 		pinctrl-names = "default";
 		reg-io-width = <4>;
@@ -1505,6 +1510,7 @@ uart5: serial@fe690000 {
 		clocks = <&cru SCLK_UART5>, <&cru PCLK_UART5>;
 		clock-names = "baudclk", "apb_pclk";
 		dmas = <&dmac0 10>, <&dmac0 11>;
+		dma-names = "tx", "rx";
 		pinctrl-0 = <&uart5m0_xfer>;
 		pinctrl-names = "default";
 		reg-io-width = <4>;
@@ -1519,6 +1525,7 @@ uart6: serial@fe6a0000 {
 		clocks = <&cru SCLK_UART6>, <&cru PCLK_UART6>;
 		clock-names = "baudclk", "apb_pclk";
 		dmas = <&dmac0 12>, <&dmac0 13>;
+		dma-names = "tx", "rx";
 		pinctrl-0 = <&uart6m0_xfer>;
 		pinctrl-names = "default";
 		reg-io-width = <4>;
@@ -1533,6 +1540,7 @@ uart7: serial@fe6b0000 {
 		clocks = <&cru SCLK_UART7>, <&cru PCLK_UART7>;
 		clock-names = "baudclk", "apb_pclk";
 		dmas = <&dmac0 14>, <&dmac0 15>;
+		dma-names = "tx", "rx";
 		pinctrl-0 = <&uart7m0_xfer>;
 		pinctrl-names = "default";
 		reg-io-width = <4>;
@@ -1547,6 +1555,7 @@ uart8: serial@fe6c0000 {
 		clocks = <&cru SCLK_UART8>, <&cru PCLK_UART8>;
 		clock-names = "baudclk", "apb_pclk";
 		dmas = <&dmac0 16>, <&dmac0 17>;
+		dma-names = "tx", "rx";
 		pinctrl-0 = <&uart8m0_xfer>;
 		pinctrl-names = "default";
 		reg-io-width = <4>;
@@ -1561,6 +1570,7 @@ uart9: serial@fe6d0000 {
 		clocks = <&cru SCLK_UART9>, <&cru PCLK_UART9>;
 		clock-names = "baudclk", "apb_pclk";
 		dmas = <&dmac0 18>, <&dmac0 19>;
+		dma-names = "tx", "rx";
 		pinctrl-0 = <&uart9m0_xfer>;
 		pinctrl-names = "default";
 		reg-io-width = <4>;
-- 
2.56.0

Re: [PATCH v2] arm64: dts: rockchip: Add dma-names to RK356x UART nodes

[Heiko Stuebner]

Am Freitag, 9. Oktober 2026, 04:01:02 Mitteleuropäische Sommerzeit schrieb Jun Yan:
> The RK356x UART nodes define a dmas property but omit the matching
> dma-names property, so the 8250 driver fails to request a DMA channel
> and falls back to PIO, logging:
> 
>   of_dma_request_slave_channel: dma-names property of node
>   '/serial@fe650000' missing or empty
> 
> Add the missing dma-names = "tx", "rx" to uart0 through uart9,
> matching other Rockchip SoCs such as the RK3588.
> 
> Fixes: a3adc0b9071d ("arm64: dts: rockchip: add core dtsi for RK3568 SoC")
> Signed-off-by: Jun Yan <jerrysteve1101@gmail.com>

Please don't do that. Uart dma can cause problems on uarts that don't
use flow-control, see [0]. So the solution of choice is to only enable
it for uarts connected to bluetooth on at least RK356x.


Heiko



[0] https://lore.kernel.org/linux-rockchip/CAMdYzYpXtMocCtCpZLU_xuWmOp2Ja_v0Aj0e6YFNRA-yV7u14g@mail.gmail.com/