linux-kernel - Re: [RFC PATCH 07/11] arm64: dts: imx8mp: fix VPU

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Message-ID: <20250528084249.6qn2mnu2rmrv7xhi@pengutronix.de>
Date: Wed, 28 May 2025 10:42:49 +0200
From: Marco Felsch <m.felsch@...gutronix.de>
To: Adam Ford <aford173@...il.com>
Cc: nicolas.dufresne@...labora.com, benjamin.gaignard@...labora.com,
	p.zabel@...gutronix.de, mchehab@...nel.org, shawnguo@...nel.org,
	Sascha Hauer <s.hauer@...gutronix.de>, kernel@...gutronix.de,
	festevam@...il.com, robh@...nel.org, krzk+dt@...nel.org,
	conor+dt@...nel.org, paulk@...-base.io, hverkuil@...all.nl,
	laurent.pinchart@...asonboard.com, sebastian.fricke@...labora.com,
	ming.qian@....com, linux-kernel@...r.kernel.org,
	linux-media@...r.kernel.org, linux-rockchip@...ts.infradead.org,
	imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
	devicetree@...r.kernel.org
Subject: Re: [RFC PATCH 07/11] arm64: dts: imx8mp: fix VPU_BUS clock setting

Hi Adam,

thanks for testing.

On 25-05-27, Adam Ford wrote:
> On Fri, May 2, 2025 at 11:55 AM Marco Felsch <m.felsch@...gutronix.de> wrote:
> >
> > On 25-05-02, Adam Ford wrote:
> > > On Fri, May 2, 2025 at 10:10 AM Marco Felsch <m.felsch@...gutronix.de> wrote:
> > > >
> > > > The VPU_PLL clock must be set before the VPU_BUS clock which is derived
> > > > from the VPU_PLL clock else the VPU_BUS clock is 300MHz and not 600MHz.
> 
> I did verify the current clock rate ends up at 300MHz instead of the
> desired 600 or 800MHz, so we should do something.
> 
> > > >
> > > > Signed-off-by: Marco Felsch <m.felsch@...gutronix.de>
> > > > ---
> > > >  arch/arm64/boot/dts/freescale/imx8mp.dtsi | 4 ++--
> > > >  1 file changed, 2 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/arch/arm64/boot/dts/freescale/imx8mp.dtsi b/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> > > > index 97b09b647ec7..7f4bdefb3480 100644
> > > > --- a/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> > > > +++ b/arch/arm64/boot/dts/freescale/imx8mp.dtsi
> > > > @@ -2289,8 +2289,8 @@ vpumix_blk_ctrl: blk-ctrl@...30000 {
> > > >                                  <&clk IMX8MP_CLK_VPU_G2_ROOT>,
> > > >                                  <&clk IMX8MP_CLK_VPU_VC8KE_ROOT>;
> > > >                         clock-names = "g1", "g2", "vc8000e";
> > > > -                       assigned-clocks = <&clk IMX8MP_CLK_VPU_BUS>, <&clk IMX8MP_VPU_PLL>;
> > > > -                       assigned-clock-parents = <&clk IMX8MP_VPU_PLL_OUT>;
> > > > +                       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>;
> > >
> > > I think there was a move to make the default be overdrive [1]  and [2]
> > > and use a 'nominal' device tree for those who are not in overdrive
> > > mode.  According to the TRM, the VPU_BUS_CLK_ROOT, the nominal is
> > > 600MHz and the overdrive is 800MHz.  Based on that, I wonder if the
> > > values here should be 800MHz and if we should add the nominal values
> > > of 600MHz to the imx8m-nominal.dtsi file.
> >
> > You're right, Ahamd and Lucas did change this. I will adapt it later on.
> 
> I updated my device tree to run in overdrive mode and ran fluster at
> the higher rates:
> VPU_G1 - 800MHz,
> VPU-G2 - 700MHz
> VPU-Bus - 800MHz
> 
> ./fluster.py run -d GStreamer-VP8-V4L2SL-Gst1.0
> Ran 57/61 tests successfully               in 5.922 secs
> (vs 7.059 secs at nominal speed)
> 
> ./fluster.py run -dGStreamer-H.264-V4L2SL-Gst1.0
> Ran 129/135 tests successfully               in 40.107 secs
> (vs 45.741 secs at nominal speed)
> 
> If you want, I can submit the clock updates I have for overdrive or
> send them to you to save you some time.

Sure, you can pick-up my patches or add new ones. Either way you're
right, the clock fixes can go in separately.

Regards,
  Marco

> 
> adam
> 
> >
> > Regards,
> >   Marco
>