[PATCH 2/2] arm: dts: Use DMTimer as Clocksource instead of counter_32k

Anurag Dutta posted 2 patches 1 month ago
There is a newer version of this series
[PATCH 2/2] arm: dts: Use DMTimer as Clocksource instead of counter_32k
Posted by Anurag Dutta 1 month ago
From: Sinthu Raja <sinthu.raja@ti.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@ti.com>
Signed-off-by: Anurag Dutta <a-dutta@ti.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@20000 {					/* 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
Re: [PATCH 2/2] arm: dts: Use DMTimer as Clocksource instead of counter_32k
Posted by Kumar, Udit 1 month ago
On 8/29/2025 2:59 PM, Anurag Dutta wrote:
> From: Sinthu Raja <sinthu.raja@ti.com>

Please check subject of patch


> 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@ti.com>
> Signed-off-by: Anurag Dutta <a-dutta@ti.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@20000 {					/* 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 */


you can reduce tab between { and comments


>   			compatible = "ti,sysc-omap4-timer", "ti,sysc";
>   			reg = <0x0 0x4>,
>   			      <0x10 0x4>;