From: Lucas Tanure <tanure@linux.com>
To: Neil Armstrong <neil.armstrong@linaro.org>,
	Kevin Hilman <khilman@baylibre.com>,
	Rob Herring <robh@kernel.org>,
	Krzysztof Kozlowski <krzk+dt@kernel.org>,
	Conor Dooley <conor+dt@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
	Xianwei Zhao <xianwei.zhao@amlogic.com>,
	linux-amlogic@lists.infradead.org,
	devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [PATCH v2 1/2] arm64: dts: amlogic: t7: use the real UART pclk
Date: Sun, 23 Aug 2026 12:53:34 +0100
Message-ID: <20260823115335.102219-2-tanure@linux.com>
In-Reply-To: <20260823115335.102219-1-tanure@linux.com>
References: <20260823115335.102219-1-tanure@linux.com>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

uart_a listed the 24MHz crystal for all three of its clocks because the
T7 clock controller driver did not exist when these boards were added.

That leaves the real UART bus clock without a user, so the kernel
turns it off when it disables unused clocks at the end of boot, and
the board hangs.

Update the board DTS files to point uart_a's pclk to CLKID_SYS_UART_A
instead of the dummy crystal clock.

Fixes: 4fef056588f5 ("arm64: dts: amlogic-t7-a311d2-khadas-vim4: add initial device-tree")
Fixes: 6f048cc7a635 ("arm64: dts: add board AN400")
Signed-off-by: Lucas Tanure <tanure@linux.com>
Assisted-by: Claude:claude-fable-5
---
 arch/arm64/boot/dts/amlogic/amlogic-t7-a311d2-an400.dts       | 2 +-
 arch/arm64/boot/dts/amlogic/amlogic-t7-a311d2-khadas-vim4.dts | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/boot/dts/amlogic/amlogic-t7-a311d2-an400.dts b/arch/arm64/boot/dts/amlogic/amlogic-t7-a311d2-an400.dts
index cab2ee9ea0d3..ca7536f772ff 100644
--- a/arch/arm64/boot/dts/amlogic/amlogic-t7-a311d2-an400.dts
+++ b/arch/arm64/boot/dts/amlogic/amlogic-t7-a311d2-an400.dts
@@ -33,7 +33,7 @@ xtal: xtal-clk {
 };
 
 &uart_a {
-	clocks = <&xtal>, <&xtal>, <&xtal>;
+	clocks = <&xtal>, <&clkc_periphs CLKID_SYS_UART_A>, <&xtal>;
 	clock-names = "xtal", "pclk", "baud";
 	status = "okay";
 };
diff --git a/arch/arm64/boot/dts/amlogic/amlogic-t7-a311d2-khadas-vim4.dts b/arch/arm64/boot/dts/amlogic/amlogic-t7-a311d2-khadas-vim4.dts
index c41525a34b72..75d81ad6830d 100644
--- a/arch/arm64/boot/dts/amlogic/amlogic-t7-a311d2-khadas-vim4.dts
+++ b/arch/arm64/boot/dts/amlogic/amlogic-t7-a311d2-khadas-vim4.dts
@@ -266,6 +266,6 @@ &sd_emmc_c {
 
 &uart_a {
 	status = "okay";
-	clocks = <&xtal>, <&xtal>, <&xtal>;
+	clocks = <&xtal>, <&clkc_periphs CLKID_SYS_UART_A>, <&xtal>;
 	clock-names = "xtal", "pclk", "baud";
 };
-- 
2.55.0