From:   Martin Blumenstingl <martin.blumenstingl@googlemail.com>
To:     linux-amlogic@lists.infradead.org, devicetree@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        jirislaby@kernel.org, neil.armstrong@linaro.org,
        krzysztof.kozlowski+dt@linaro.org, robh+dt@kernel.org,
        gregkh@linuxfoundation.org,
        Christian Hewitt <christianshewitt@gmail.com>,
        Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Subject: [PATCH v2 3/3] arm64: dts: meson-g12-common: Use the G12A UART compatible string
Date:   Mon,  6 Mar 2023 20:42:23 +0100
Message-Id: <20230306194223.1869814-4-martin.blumenstingl@googlemail.com>
In-Reply-To: <20230306194223.1869814-1-martin.blumenstingl@googlemail.com>
References: <20230306194223.1869814-1-martin.blumenstingl@googlemail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

Switch meson-12-common.dtsi to use the Meson G12A specific UART
compatible string. This enables the "divide XTAL by 2" divider which
improves support for UART attached Bluetooth modules (for example
RTL8822CS) running at a baud rate of 1500000. Without dividing XTAL
(24MHz) by 2 a baud rate of 1500000 cannot be generated cleanly and the
resulting jitter breaks communication with the module.

Tested-by: Christian Hewitt <christianshewitt@gmail.com>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
---
Greg, please don't take this through your tree. I included this patch
to show the overall goal of this series. If Neil won't take this as
part of another series then I'll send it separately.

Changes from v1 -> v2:
- keep meson-gx-uart as fallback compatible string


 arch/arm64/boot/dts/amlogic/meson-g12-common.dtsi | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/arch/arm64/boot/dts/amlogic/meson-g12-common.dtsi b/arch/arm64/boot/dts/amlogic/meson-g12-common.dtsi
index 123a56f7f818..904bcd4d2acf 100644
--- a/arch/arm64/boot/dts/amlogic/meson-g12-common.dtsi
+++ b/arch/arm64/boot/dts/amlogic/meson-g12-common.dtsi
@@ -2046,7 +2046,8 @@ pwm_AO_cd: pwm@2000 {
 			};
 
 			uart_AO: serial@3000 {
-				compatible = "amlogic,meson-gx-uart",
+				compatible = "amlogic,meson-g12a-uart",
+					     "amlogic,meson-gx-uart",
 					     "amlogic,meson-ao-uart";
 				reg = <0x0 0x3000 0x0 0x18>;
 				interrupts = <GIC_SPI 193 IRQ_TYPE_EDGE_RISING>;
@@ -2056,7 +2057,8 @@ uart_AO: serial@3000 {
 			};
 
 			uart_AO_B: serial@4000 {
-				compatible = "amlogic,meson-gx-uart",
+				compatible = "amlogic,meson-g12a-uart",
+					     "amlogic,meson-gx-uart",
 					     "amlogic,meson-ao-uart";
 				reg = <0x0 0x4000 0x0 0x18>;
 				interrupts = <GIC_SPI 197 IRQ_TYPE_EDGE_RISING>;
@@ -2293,7 +2295,8 @@ clk_msr: clock-measure@18000 {
 			};
 
 			uart_C: serial@22000 {
-				compatible = "amlogic,meson-gx-uart";
+				compatible = "amlogic,meson-g12a-uart",
+					     "amlogic,meson-gx-uart";
 				reg = <0x0 0x22000 0x0 0x18>;
 				interrupts = <GIC_SPI 93 IRQ_TYPE_EDGE_RISING>;
 				clocks = <&xtal>, <&clkc CLKID_UART2>, <&xtal>;
@@ -2302,7 +2305,8 @@ uart_C: serial@22000 {
 			};
 
 			uart_B: serial@23000 {
-				compatible = "amlogic,meson-gx-uart";
+				compatible = "amlogic,meson-g12a-uart",
+					     "amlogic,meson-gx-uart";
 				reg = <0x0 0x23000 0x0 0x18>;
 				interrupts = <GIC_SPI 75 IRQ_TYPE_EDGE_RISING>;
 				clocks = <&xtal>, <&clkc CLKID_UART1>, <&xtal>;
@@ -2311,7 +2315,8 @@ uart_B: serial@23000 {
 			};
 
 			uart_A: serial@24000 {
-				compatible = "amlogic,meson-gx-uart";
+				compatible = "amlogic,meson-g12a-uart",
+					     "amlogic,meson-gx-uart";
 				reg = <0x0 0x24000 0x0 0x18>;
 				interrupts = <GIC_SPI 26 IRQ_TYPE_EDGE_RISING>;
 				clocks = <&xtal>, <&clkc CLKID_UART0>, <&xtal>;
-- 
2.39.2