linux-kernel - [PATCH] arm64: dts: rockchip: rk3328: Fix UART pull-ups

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Date:   Fri,  4 Dec 2020 14:48:05 +0800
From:   Chen-Yu Tsai <wens@...nel.org>
To:     Heiko Stuebner <heiko@...ech.de>, Rob Herring <robh+dt@...nel.org>
Cc:     Chen-Yu Tsai <wens@...e.org>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: [PATCH] arm64: dts: rockchip: rk3328: Fix UART pull-ups

From: Chen-Yu Tsai <wens@...e.org>

For UARTs, the local pull-ups should be on the RX pin, not the TX pin.
UARTs transmit active-low, so a disconnected RX pin should be pulled
high instead of left floating to prevent noise being interpreted as
transmissions.

This gets rid of bogus sysrq events when the UART console is not
connected.

Fixes: 52e02d377a72 ("arm64: dts: rockchip: add core dtsi file for RK3328 SoCs")
Signed-off-by: Chen-Yu Tsai <wens@...e.org>
---
 arch/arm64/boot/dts/rockchip/rk3328.dtsi | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/arch/arm64/boot/dts/rockchip/rk3328.dtsi b/arch/arm64/boot/dts/rockchip/rk3328.dtsi
index 521c4678ec35..1e3aa6acbc11 100644
--- a/arch/arm64/boot/dts/rockchip/rk3328.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3328.dtsi
@@ -1265,8 +1265,8 @@ otp_out: otp-out {
 
 		uart0 {
 			uart0_xfer: uart0-xfer {
-				rockchip,pins = <1 RK_PB1 1 &pcfg_pull_up>,
-						<1 RK_PB0 1 &pcfg_pull_none>;
+				rockchip,pins = <1 RK_PB1 1 &pcfg_pull_none>,
+						<1 RK_PB0 1 &pcfg_pull_up>;
 			};
 
 			uart0_cts: uart0-cts {
@@ -1284,8 +1284,8 @@ uart0_rts_pin: uart0-rts-pin {
 
 		uart1 {
 			uart1_xfer: uart1-xfer {
-				rockchip,pins = <3 RK_PA4 4 &pcfg_pull_up>,
-						<3 RK_PA6 4 &pcfg_pull_none>;
+				rockchip,pins = <3 RK_PA4 4 &pcfg_pull_none>,
+						<3 RK_PA6 4 &pcfg_pull_up>;
 			};
 
 			uart1_cts: uart1-cts {
@@ -1303,15 +1303,15 @@ uart1_rts_pin: uart1-rts-pin {
 
 		uart2-0 {
 			uart2m0_xfer: uart2m0-xfer {
-				rockchip,pins = <1 RK_PA0 2 &pcfg_pull_up>,
-						<1 RK_PA1 2 &pcfg_pull_none>;
+				rockchip,pins = <1 RK_PA0 2 &pcfg_pull_none>,
+						<1 RK_PA1 2 &pcfg_pull_up>;
 			};
 		};
 
 		uart2-1 {
 			uart2m1_xfer: uart2m1-xfer {
-				rockchip,pins = <2 RK_PA0 1 &pcfg_pull_up>,
-						<2 RK_PA1 1 &pcfg_pull_none>;
+				rockchip,pins = <2 RK_PA0 1 &pcfg_pull_none>,
+						<2 RK_PA1 1 &pcfg_pull_up>;
 			};
 		};
 
-- 
2.29.2