linux-kernel - Re: [PATCH 2/3] ARM: DRA7x: dts: Fix the 32kHz clock calculation

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Date:	Wed, 27 Apr 2016 14:40:14 +0300
From:	Tero Kristo <t-kristo@...com>
To:	"J.D. Schroeder" <Linux.HWI@...min.com>,
	<linux-kernel@...r.kernel.org>, <bcousson@...libre.com>,
	<tony@...mide.com>, <robh+dt@...nel.org>, <pawel.moll@....com>,
	<mark.rutland@....com>, <ijc+devicetree@...lion.org.uk>,
	<galak@...eaurora.org>, <linux@....linux.org.uk>,
	<linux-omap@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>
CC:	"J.D. Schroeder" <jay.schroeder@...min.com>,
	"J, Keerthy" <j-keerthy@...com>
Subject: Re: [PATCH 2/3] ARM: DRA7x: dts: Fix the 32kHz clock calculation

On 26/04/16 20:54, J.D. Schroeder wrote:
> From: "J.D. Schroeder" <jay.schroeder@...min.com>
>
> This commit fixes the 32kHz clock (sys_32k_ck) calculation to be
> correctly based on the SYS_CLK1 (sys_clkin1) frequency. Based on the
> TRM CTRL_CORE_BOOTSTRAP[9:8] SPEEDSELECT, set by the SYSBOOT[9:8]
> board jumpers according to the SYS_CLK1 frequency, the frequency of
> the 32kHz FUNC_32K_CLK is set to SYS_CLK1/610. The following
> sys_32k_ck frequencies get used for different SYS_CLK1 frequencies:
>          0b00: Unknown  -> 32768 Hz crystal from CLKIN_32K pin
>          0b01: 20   MHz -> 32787 Hz clock (SYS_CLK1/610)
>          0b10: 27   MHz -> 44262 Hz clock (SYS_CLK1/610)
>          0b11: 19.2 MHz -> 31475 Hz clock (SYS_CLK1/610)
>
> Signed-off-by: J.D. Schroeder <jay.schroeder@...min.com>
> Reviewed-by: Ben McCauley <ben.mccauley@...min.com>

A patch doing the same thing is already in mainline, see:

commit eea08802f586acd6aef377d1b4a541821013cc0b
Author: Keerthy <j-keerthy@...com>
Date:   Mon Apr 4 11:07:15 2016 +0530

     ARM: dts: dra7: Correct clock tree for sys_32k_ck

So, this one can be ignored.

-Tero

> ---
>   arch/arm/boot/dts/dra7xx-clocks.dtsi | 28 ++++++++++++++++++++++------
>   1 file changed, 22 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm/boot/dts/dra7xx-clocks.dtsi b/arch/arm/boot/dts/dra7xx-clocks.dtsi
> index 9d1a583..a514fc3 100644
> --- a/arch/arm/boot/dts/dra7xx-clocks.dtsi
> +++ b/arch/arm/boot/dts/dra7xx-clocks.dtsi
> @@ -98,12 +98,6 @@
>   		clock-frequency = <32768>;
>   	};
>
> -	sys_32k_ck: sys_32k_ck {
> -		#clock-cells = <0>;
> -		compatible = "fixed-clock";
> -		clock-frequency = <32768>;
> -	};
> -
>   	virt_12000000_ck: virt_12000000_ck {
>   		#clock-cells = <0>;
>   		compatible = "fixed-clock";
> @@ -2177,4 +2171,26 @@
>   		ti,bit-shift = <22>;
>   		reg = <0x0558>;
>   	};
> +
> +	sys_32kin: sys_32kin {
> +		#clock-cells = <0>;
> +		compatible = "fixed-clock";
> +		clock-frequency = <32768>;
> +	};
> +
> +	sys_clkin1_32k_div: sys_clkin1_32k_div {
> +		#clock-cells = <0>;
> +		compatible = "fixed-factor-clock";
> +		clocks = <&sys_clkin1>;
> +		clock-mult = <1>;
> +		clock-div = <610>;
> +	};
> +
> +	sys_32k_ck: sys_32k_ck {
> +		#clock-cells = <0>;
> +		compatible = "ti,mux-clock";
> +		clocks = <&sys_32kin>, <&sys_clkin1_32k_div>, <&sys_clkin1_32k_div>, <&sys_clkin1_32k_div>;
> +		ti,bit-shift = <8>;
> +		reg = <0x06c4>;
> +	};
>   };
>