xx_vv_immortalwrt/target/linux/bcm27xx/patches-6.6/950-1560-dts-rp1-Don-t-use-DMA-with-UARTs.patch
Álvaro Fernández Rojas 4618d09587 bcm27xx: pull 6.6 patches from RPi repo
Adds latest 6.6 patches from the Raspberry Pi repository.

These patches were generated from:
https://github.com/raspberrypi/linux/commits/rpi-6.6.y/
With the following command:
git format-patch -N v6.6.85..HEAD
(HEAD -> bba53a117a4a5c29da892962332ff1605990e17a)

Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
2025-04-10 10:36:23 +02:00

34 lines
1.3 KiB
Diff

From bba53a117a4a5c29da892962332ff1605990e17a Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.com>
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 <phil@raspberrypi.com>
---
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 = <RP1_INT_UART0 IRQ_TYPE_LEVEL_HIGH>;
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;