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Subject: Re: [PATCH 4/5] ARM: Add basic support for EcoNet EN7523 SoC
To:     Geert Uytterhoeven <geert@linux-m68k.org>
Cc:     Arnd Bergmann <arnd@arndb.de>, DTML <devicetree@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Russell King <linux@armlinux.org.uk>,
        Linus Walleij <linus.walleij@linaro.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        Anshuman Khandual <anshuman.khandual@arm.com>,
        Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
        John Crispin <john@phrozen.org>,
        Ard Biesheuvel <ardb@kernel.org>,
        YiFei Zhu <yifeifz2@illinois.edu>,
        Mike Rapoport <rppt@kernel.org>,
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        Kees Cook <keescook@chromium.org>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        Viresh Kumar <viresh.kumar@linaro.org>,
        Felix Fietkau <nbd@nbd.name>
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From:   Bert Vermeulen <bert@biot.com>
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Date:   Mon, 9 Aug 2021 15:00:12 +0200
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On 8/9/21 2:46 PM, Geert Uytterhoeven wrote:
>> I didn't make that patch, but it turns out it's needed to get PSCI working;
>> detection hangs without it. That makes no sense to me, but I'll examine further.
> 
> Probably PSCI relies on the memory contents at the start of RAM not
> being overwritten?

It turns out to hang at the first SMC call, for PSCI_0_2_FN_PSCI_VERSION. I 
assume the receiver of that call, ATF, got dropped in that region by the 
vendor's U-Boot.

> Does it help if you remove the first 512 KiB from the /memory node
> (which should be declared in en7523-evb.dts instead of en7523.dtsi
> BTW)?
No it doesn't, was just trying to work out why not, in your 
fdt_check_mem_start().

Anyway that was Arnd's first suggestion, but I think his second suggestion 
(teach fdt_check_mem_start() about /memreserve/) is the cleaner approach to 
this. Opinions?


-- 
Bert Vermeulen
bert@biot.com