From bba53a117a4a5c29da892962332ff1605990e17a Mon Sep 17 00:00:00 2001 From: Phil Elwell Date: Wed, 26 Mar 2025 11:28:28 +0000 Subject: [PATCH] dts: rp1: Don't use DMA with UARTs DMA has been enabled on RP1's UART0, but with mixed success. Transmits seem to work, but the DMA interface is not well suited to receiving arbitrary amounts of data. In particular, the PL011 driver is slow to pass on the received data, batching it into large blocks. On balance, it's better to just disable the DMA support. As with the other UARTs, the required runes are left in the DTS as comments. Signed-off-by: Phil Elwell --- arch/arm64/boot/dts/broadcom/rp1.dtsi | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/arch/arm64/boot/dts/broadcom/rp1.dtsi +++ b/arch/arm64/boot/dts/broadcom/rp1.dtsi @@ -65,9 +65,9 @@ interrupts = ; clocks = <&rp1_clocks RP1_CLK_UART &rp1_clocks RP1_PLL_SYS_PRI_PH>; clock-names = "uartclk", "apb_pclk"; - dmas = <&rp1_dma RP1_DMA_UART0_TX>, - <&rp1_dma RP1_DMA_UART0_RX>; - dma-names = "tx", "rx"; + // dmas = <&rp1_dma RP1_DMA_UART0_TX>, + // <&rp1_dma RP1_DMA_UART0_RX>; + // dma-names = "tx", "rx"; pinctrl-names = "default"; arm,primecell-periphid = <0x00341011>; uart-has-rtscts;