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From:   Detlev Casanova <detlev.casanova@collabora.com>
To:     Geert Uytterhoeven <geert@linux-m68k.org>
Cc:     linux-kernel@vger.kernel.org, Magnus Damm <magnus.damm@gmail.com>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        "open list:ARM/RENESAS ARCHITECTURE" 
        <linux-renesas-soc@vger.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>
Subject: Re: [PATCH] arm64: dts: renesas: r8a77951: Add reserved memory region
Date:   Mon, 14 Nov 2022 15:03:07 -0500
Message-ID: <12113751.O9o76ZdvQC@falcon9>
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References: <20221114194846.108814-1-detlev.casanova@collabora.com> <CAMuHMdW9dAxJwzD=W1xLN2e_T_BNFk5MfbWh24Btur-o+-n4sg@mail.gmail.com>
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On Monday, November 14, 2022 2:57:21 P.M. EST Geert Uytterhoeven wrote:
> Hi Detlev,
> 
> On Mon, Nov 14, 2022 at 8:48 PM Detlev Casanova
> 
> <detlev.casanova@collabora.com> wrote:
> > The 0x3000000 bytes memory region starting at 0x54000000 is
> > reserved for the lossy_decompression hardware that will try to
> > decompress any data written in the region.
> > 
> > Mark the region as no-map to prevent linux from using it as RAM.
> > 
> > Signed-off-by: Detlev Casanova <detlev.casanova@collabora.com>
> 
> Thanks for your patch!
> 
> > --- a/arch/arm64/boot/dts/renesas/r8a77951.dtsi
> > +++ b/arch/arm64/boot/dts/renesas/r8a77951.dtsi
> > @@ -290,6 +290,18 @@ CPU_SLEEP_1: cpu-sleep-1 {
> > 
> >                 };
> >         
> >         };
> > 
> > +       reserved-memory {
> > +               #address-cells = <2>;
> > +               #size-cells = <2>;
> > +               ranges;
> > +
> > +               /* device specific region for Lossy Decompression */
> > +               lossy_decompress: memory-region@54000000 {
> > +                       no-map;
> > +                       reg = <0x00000000 0x54000000 0x0 0x03000000>;
> > +               };
> > +       };
> 
> This depends on the firmware/boot loader stack.  If it configures a
> Lossy Decompression region, it should make sure to pass this
> info through the various boot loader components to Linux,
> just like is already done with the memory regions, RPC-IF state,
> and OpTee configuration.

Thanks for your fast answer ! I didn't realise ATF was doing that, I probably 
have a configuration issue in ATF then, I'll rebuild and start from there.

Thanks !

> Gr{oetje,eeting}s,
> 
>                         Geert