linux-kernel - [PATCH 2/2] arm: dts: Use DMTimer as Clocksource instead of counter

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Message-ID: <20250829092947.855974-3-a-dutta@ti.com>
Date: Fri, 29 Aug 2025 14:59:47 +0530
From: Anurag Dutta <a-dutta@...com>
To: <aaro.koskinen@....fi>, <andreas@...nade.info>, <khilman@...libre.com>,
        <rogerq@...nel.org>, <tony@...mide.com>
CC: <linux-omap@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <u-kumar1@...com>, <vigneshr@...com>
Subject: [PATCH 2/2] arm: dts: Use DMTimer as Clocksource instead of counter_32k

From: Sinthu Raja <sinthu.raja@...com>

Clock drift of approximately 500 ppm is observed with 'counter_32k'
as clocksource. Clock drift is seen because 'counter_32k' is running
with 32786Hz frequency instead it should run with 32768Hz. Use DMTimer as
clocksource, which is running at 32768Hz to fix the clock drift issue.

Signed-off-by: Sinthu Raja <sinthu.raja@...com>
Signed-off-by: Anurag Dutta <a-dutta@...com>
---
 arch/arm/boot/dts/ti/omap/am57xx-beagle-x15.dts | 9 +++++++++
 arch/arm/boot/dts/ti/omap/dra7-l4.dtsi          | 2 +-
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/arch/arm/boot/dts/ti/omap/am57xx-beagle-x15.dts b/arch/arm/boot/dts/ti/omap/am57xx-beagle-x15.dts
index 0a8b16505ed9..83009883277e 100644
--- a/arch/arm/boot/dts/ti/omap/am57xx-beagle-x15.dts
+++ b/arch/arm/boot/dts/ti/omap/am57xx-beagle-x15.dts
@@ -36,3 +36,12 @@ &mmc2 {
 &phy1 {
 	max-speed = <100>;
 };
+
+&timer12_target {
+	ti,no-reset-on-init;
+	ti,no-idle;
+};
+
+&counter32k {
+	status = "disabled";
+};
diff --git a/arch/arm/boot/dts/ti/omap/dra7-l4.dtsi b/arch/arm/boot/dts/ti/omap/dra7-l4.dtsi
index ba7fdaae9c6e..a6ac4fd43b54 100644
--- a/arch/arm/boot/dts/ti/omap/dra7-l4.dtsi
+++ b/arch/arm/boot/dts/ti/omap/dra7-l4.dtsi
@@ -4439,7 +4439,7 @@ segment@...00 {					/* 0x4ae20000 */
 			 <0x0000c000 0x0002c000 0x001000>,	/* ap 29 */
 			 <0x0000f000 0x0002f000 0x001000>;	/* ap 32 */
 
-		target-module@0 {			/* 0x4ae20000, ap 19 08.0 */
+		timer12_target: target-module@0 {			/* 0x4ae20000, ap 19 08.0 */
 			compatible = "ti,sysc-omap4-timer", "ti,sysc";
 			reg = <0x0 0x4>,
 			      <0x10 0x4>;
-- 
2.34.1