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

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Message-ID: <CAHCN7xKjEt3rq4VUOSSTqcT4SyWxSCPLHGf6jR6KVHvor5wfKQ@mail.gmail.com>
Date: Mon, 2 Jun 2025 10:35:46 -0500
From: Adam Ford <aford173@...il.com>
To: Marco Felsch <m.felsch@...gutronix.de>
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

On Sun, Jun 1, 2025 at 1:36 PM Marco Felsch <m.felsch@...gutronix.de> wrote:
>
> 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.

I think you're right.  I'll fix that up and do a V2.  I forgot to add
my own s-o-b tag, so I'll fix that too.  I'll try to do it this week.

adam
>
> Regards,
>   Marco