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Date:   Sat, 22 Oct 2022 15:51:16 +0100
From:   Jonathan McDowell <noodles@earth.li>
To:     Linus Walleij <linus.walleij@linaro.org>
Cc:     Christian Marangi <ansuelsmth@gmail.com>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Russell King <linux@armlinux.org.uk>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <andersson@kernel.org>,
        Konrad Dybcio <konrad.dybcio@somainline.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Ard Biesheuvel <ardb@kernel.org>,
        "Russell King (Oracle)" <rmk+kernel@armlinux.org.uk>,
        Nick Hawkins <nick.hawkins@hpe.com>,
        John Crispin <john@phrozen.org>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-arm-msm@vger.kernel.org
Subject: Re: [PATCH] ARM: mach-qcom: fix support for ipq806x
Message-ID: <Y1QDZMoCeYAfeO6j@earth.li>
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On Sat, Oct 22, 2022 at 04:21:28PM +0200, Linus Walleij wrote:
> On Fri, Oct 21, 2022 at 11:55 PM Christian Marangi <ansuelsmth@gmail.com> wrote:
> > On Fri, Oct 21, 2022 at 11:44:56PM +0200, Linus Walleij wrote:
> 
> > > Is it not possible to use Geert's linux,usable-memory-range in
> > > the chosen node to make the kernel stay off the memory?
> > > (See examples by grep usable-memory in the kernel.)
> > >
> > just to confirm this is one of the example you are suggesting?
> >
> > chosen {
> >                 bootargs = "console=ttyS0,115200 earlycon";
> >                 stdout-path = "serial0:115200n8";
> >                 linux,usable-memory-range = <0x80200000 0x1fe00000>;
> >         };
> 
> Yep that thing!
> 
> > Main problem here is that uboot in some case doesn't support dt and pass
> > wrong ATAGS (with the memory not reserved) and AUTO_ZRELADDR calculate
> > the wrong addr I assume?
> 
> You do have a DTB right, just that it is attached, and then the kernel
> uses the ATAGs to augment the memory?
> 
> In that case what about disabling ARM_ATAG_DTB_COMPAT
> and adding the actual valid memory to the top-level DTS
> file? Just like that:
> 
>       memory {
>                 device_type = "memory";
>                 reg = <0x42000000 0xnnnnnnnn>;
>         };

The RB3011 (arch/arm/boot/dts/qcom-ipq8064-rb3011.dts) does this and has
been working fine with AUTO_ZRELADDR (and no ATAGS support enabled) - I
have a recollection it didn't used to, but it's certainly worked since
the 5.15 timeframe.

J.

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