linux-kernel - Re: [PATCH 3/3] arm64: dts: imx8qxp: add cache info

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Message-ID: <20211209223103.br2scdg2j6gpfnpl@bogus>
Date:   Thu, 9 Dec 2021 22:31:03 +0000
From:   Sudeep Holla <sudeep.holla@....com>
To:     Rob Herring <robh+dt@...nel.org>
Cc:     "Peng Fan (OSS)" <peng.fan@....nxp.com>,
        Shawn Guo <shawnguo@...nel.org>,
        Sudeep Holla <sudeep.holla@....com>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Sascha Hauer <kernel@...gutronix.de>,
        Fabio Estevam <festevam@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Lucas Stach <l.stach@...gutronix.de>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        devicetree@...r.kernel.org,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Peng Fan <peng.fan@....com>
Subject: Re: [PATCH 3/3] arm64: dts: imx8qxp: add cache info

On Thu, Dec 09, 2021 at 04:15:09PM -0600, Rob Herring wrote:
> On Fri, Nov 12, 2021 at 12:27 AM Peng Fan (OSS) <peng.fan@....nxp.com> wrote:
> >
> > From: Peng Fan <peng.fan@....com>
> >
> > i.MX8QXP A35 Cluster has 32KB Icache, 32KB Dcache and 512KB L2 Cache
> >  - Icache is 2-way set associative
> >  - Dcache is 4-way set associative
> >  - L2cache is 8-way set associative
> >  - Line size are 64bytes
> >
> > Signed-off-by: Peng Fan <peng.fan@....com>
> > ---
> >  arch/arm64/boot/dts/freescale/imx8qxp.dtsi | 28 ++++++++++++++++++++++
> >  1 file changed, 28 insertions(+)
> >
> > diff --git a/arch/arm64/boot/dts/freescale/imx8qxp.dtsi b/arch/arm64/boot/dts/freescale/imx8qxp.dtsi
> > index 617618edf77e..dbec7c106e0b 100644
> > --- a/arch/arm64/boot/dts/freescale/imx8qxp.dtsi
> > +++ b/arch/arm64/boot/dts/freescale/imx8qxp.dtsi
> > @@ -58,6 +58,12 @@ A35_0: cpu@0 {
> >                         compatible = "arm,cortex-a35";
> >                         reg = <0x0 0x0>;
> >                         enable-method = "psci";
> > +                       i-cache-size = <0x8000>;
> > +                       i-cache-line-size = <64>;
> > +                       i-cache-sets = <256>;
> > +                       d-cache-size = <0x8000>;
> > +                       d-cache-line-size = <64>;
> > +                       d-cache-sets = <128>;
> 
> Why do you need all this for the L1? Isn't it discoverable with cache
> ID registers?
> 

No, not after the following:
Commit a8d4636f96ad ("arm64: cacheinfo: Remove CCSIDR-based cache information probing")

which removed ID register based cache probing and we now expect to obtain
the same via DT/ACPI unfortunately.

-- 
Regards,
Sudeep