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References: <20211213195833.772892-1-dbrazdil@google.com> <20211213195833.772892-2-dbrazdil@google.com>
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From:   Rob Herring <robh@kernel.org>
Date:   Thu, 16 Dec 2021 09:21:00 -0600
Message-ID: <CAL_JsqJRpNr7McM9OJcPs095ZfAqGJfN7FhGhy7i6pN+tx1MGg@mail.gmail.com>
Subject: Re: [PATCH v3 1/2] dt-bindings: firmware: Add Open Profile for DICE
To:     David Brazdil <dbrazdil@google.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Arnd Bergmann <arnd@arndb.de>, Will Deacon <will@kernel.org>,
        Andrew Scull <ascull@google.com>, devicetree@vger.kernel.org,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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On Wed, Dec 15, 2021 at 3:08 PM David Brazdil <dbrazdil@google.com> wrote:
>
> Hi Rob,
>
> > > +        dice_reserved: dice@12340000 {
> > > +            reg = <0x00 0x12340000 0x2000>;
> > > +            no-map;
> > > +        };
> > > +    };
> > > +
> > > +    dice {
> > > +        compatible = "google,open-dice";
> > > +        memory-region = <&dice_reserved>;
> >
> > There's no need for this indirection. Just add the compatible to the
> > dice@12340000 node. You can bind drivers to /reserved-memory nodes.
>
> I have not found a way to make that work for kernel modules. Built-in
> drivers can bind with RESERVEDMEM_OF_DECLARE, which puts an entry in
> __reservedmem_of_table and __reserved_mem_init_node() iterates find it
> there. A good case study might be CONFIG_TEGRA210_EMC, where the driver
> itself can be a module but the rmem parsing is always built-in under
> CONFIG_TEGRA210_EMC_TABLE. I don't think that's worth the trouble with
> this driver.

I forgot you have to add the compatible to reserved_mem_matches in
drivers/of/platform.c.

Rob