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

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Message-ID: <bea3ce38-b78a-4ed2-a128-3f6643308adb@ti.com>
Date: Fri, 29 Aug 2025 19:55:36 +0530
From: "Kumar, Udit" <u-kumar1@...com>
To: Anurag Dutta <a-dutta@...com>, <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>,
        <vigneshr@...com>, <u-kumar1@...com>
Subject: Re: [PATCH 2/2] arm: dts: Use DMTimer as Clocksource instead of
 counter_32k


On 8/29/2025 2:59 PM, Anurag Dutta wrote:
> From: Sinthu Raja <sinthu.raja@...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@...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 */


you can reduce tab between { and comments


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