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Message-ID: <8db31b08-5a8b-f317-a954-c228a08004a8@phytec.de>
Date:   Fri, 5 May 2023 15:38:14 +0200
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Subject: Re: [PATCH 2/2] arm64: dts: ti: Add basic support for
 phyBOARD-Lyra-AM625
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To:     Tony Lindgren <tony@atomide.com>, Nishanth Menon <nm@ti.com>
CC:     <linux-kernel@vger.kernel.org>, <devicetree@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-hardening@vger.kernel.org>, <upstream@lists.phytec.de>,
        <vigneshr@ti.com>, <kristo@kernel.org>, <robh+dt@kernel.org>,
        <krzysztof.kozlowski+dt@linaro.org>, <keescook@chromium.org>,
        <tony.luck@intel.com>, <gpiccoli@igalia.com>
References: <20230504140143.1425951-1-w.egorov@phytec.de>
 <20230504140143.1425951-2-w.egorov@phytec.de>
 <20230504142643.pkzsftrsrqph4vql@banked> <20230505093930.GS14287@atomide.com>
From:   Wadim Egorov <w.egorov@phytec.de>
In-Reply-To: <20230505093930.GS14287@atomide.com>
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Am 05.05.23 um 11:39 schrieb Tony Lindgren:
> * Nishanth Menon <nm@ti.com> [230504 14:33]:
>> Just wondering: if the carrier board can easily work with different
>> SoMs.. in which case, we could do overlay to create the som + carrier
>> overlay to create rdk dtb - this might allow the scheme to scale to
>> additional SoMs and carrier combinations.. and the SoM dtb could be
>> sufficient for something like a bootloader.
> It might be best to limit the overlay usage to devices that might see
> dual use on the carrier board.. Not sure if setting up the entire
> carrier board makes sense as an overlay :) Not sure if folks want to
> debug boot issues on a remote server for example if an overlay is
> needed to boot with Ethernet :)

Our idea is to create overlays for SoM variants, e.g. an overlay for a SoM 
without SPI NOR flash populated.
If we want to reuse a carrier board, we could factor out the carrier board dts 
into a dtsi file and provide the needed combinations in form of different dts files.

In the bootloader world the situation is a bit different.
Here we would like to have a universal phycore_am62x "board" that should be able 
to handle most carrier board designs using that SoM. And since u-boot is moving 
towards having a single source of device trees, this concept will probably no 
longer work anymore. So your idea with a SoM dtb sounds interesting.
I wonder what ideas other SoM vendors have or how it is handled on other 
architectures.

Regards,
Wadim

>
> Regards,
>
> Tony