linux-kernel - Re: [PATCH 4/4] arm64: dts: imx8mp: Configure VPU clocks for overdrive

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Message-ID: <20250601183620.npuicmipv6kv54z6@pengutronix.de>
Date: Sun, 1 Jun 2025 20:36:20 +0200
From: Marco Felsch <m.felsch@...gutronix.de>
To: Adam Ford <aford173@...il.com>
Cc: linux-arm-kernel@...ts.infradead.org, aford@...conembedded.com,
	Rob Herring <robh@...nel.org>,
	Krzysztof Kozlowski <krzk+dt@...nel.org>,
	Conor Dooley <conor+dt@...nel.org>, Shawn Guo <shawnguo@...nel.org>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Fabio Estevam <festevam@...il.com>, devicetree@...r.kernel.org,
	imx@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/4] arm64: dts: imx8mp: Configure VPU clocks for
 overdrive

Hi Adam,

thanks for the patch.

On 25-05-30, Adam Ford wrote:
> The defaults for this SoC are configured for overdrive mode, but
> the VPU clocks are currently configured for nominal mode.
> Increase VPU_G1_CLK_ROOT to 800MHZ from 600MHz,
> Increase VPU_G2_CLK_ROOT to 700MHZ from 500MHz, and
> Increase VPU_BUS_CLK_ROOT to 800MHz from 600MHz.
> 
> This requires adjusting the clock parents. Since there is already
> 800MHz clock references, move the VPU_BUS and G1 clocks to it.
> This frees up the VPU_PLL to be configured at 700MHz to run
> the G2 clock at 700MHz.
> 
> Signed-off-by: Adam Ford <aford173@...il.com>
> ---
>  arch/arm64/boot/dts/freescale/imx8mp.dtsi | 12 ++++++------
>  1 file changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/freescale/imx8mp.dtsi b/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> index 909555a5da4b..848b25c9b752 100644
> --- a/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> +++ b/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> @@ -2256,8 +2256,8 @@ vpu_g1: video-codec@...00000 {
>  			interrupts = <GIC_SPI 7 IRQ_TYPE_LEVEL_HIGH>;
>  			clocks = <&clk IMX8MP_CLK_VPU_G1_ROOT>;
>  			assigned-clocks = <&clk IMX8MP_CLK_VPU_G1>;
> -			assigned-clock-parents = <&clk IMX8MP_VPU_PLL_OUT>;
> -			assigned-clock-rates = <600000000>;
> +			assigned-clock-parents = <&clk IMX8MP_SYS_PLL1_800M>;
> +			assigned-clock-rates = <800000000>;
>  			power-domains = <&vpumix_blk_ctrl IMX8MP_VPUBLK_PD_G1>;
>  		};
>  
> @@ -2267,8 +2267,8 @@ vpu_g2: video-codec@...10000 {
>  			interrupts = <GIC_SPI 8 IRQ_TYPE_LEVEL_HIGH>;
>  			clocks = <&clk IMX8MP_CLK_VPU_G2_ROOT>;
>  			assigned-clocks = <&clk IMX8MP_CLK_VPU_G2>;
> -			assigned-clock-parents = <&clk IMX8MP_SYS_PLL2_1000M>;
> -			assigned-clock-rates = <500000000>;
> +			assigned-clock-parents = <&clk IMX8MP_VPU_PLL_OUT>;
> +			assigned-clock-rates = <700000000>;
>  			power-domains = <&vpumix_blk_ctrl IMX8MP_VPUBLK_PD_G2>;
>  		};
>  
> @@ -2284,8 +2284,8 @@ vpumix_blk_ctrl: blk-ctrl@...30000 {
>  				 <&clk IMX8MP_CLK_VPU_VC8KE_ROOT>;
>  			clock-names = "g1", "g2", "vc8000e";
>  			assigned-clocks = <&clk IMX8MP_VPU_PLL>, <&clk IMX8MP_CLK_VPU_BUS>;
> -			assigned-clock-parents = <0>, <&clk IMX8MP_VPU_PLL_OUT>;
> -			assigned-clock-rates = <600000000>, <600000000>;
> +			assigned-clock-parents = <0>, <&clk IMX8MP_SYS_PLL1_800M>;
> +			assigned-clock-rates = <700000000>, <800000000>;

I think we can drop the "assigned-clocks = <&clk IMX8MP_VPU_PLL>" part
completely.

Before your patch the IMX8MP_VPU_PLL_OUT was used as clock-parent for
the IMX8MP_CLK_VPU_BUS. With yout patch IMX8MP_SYS_PLL1_800M is used.

Regards,
  Marco