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@xxxxxxxxx>

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@xxxxxxxxxxxxxx/