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References: <20231004150856.2540-1-jszhang@kernel.org>
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From:   Geert Uytterhoeven <geert@linux-m68k.org>
Date:   Thu, 5 Oct 2023 14:57:36 +0200
Message-ID: <CAMuHMdVfnn2YiorGQeVqa7cQmXVDQhiqoY6dSktA6myuE6LRsw@mail.gmail.com>
Subject: Re: [PATCH] soc: renesas: make ARCH_R9A07G043 (riscv version) depend
 on NONPORTABLE
To:     Jisheng Zhang <jszhang@kernel.org>
Cc:     Magnus Damm <magnus.damm@gmail.com>,
        Paul Walmsley <paul.walmsley@sifive.com>,
        Palmer Dabbelt <palmer@dabbelt.com>,
        Albert Ou <aou@eecs.berkeley.edu>,
        Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>,
        linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org,
        linux-riscv@lists.infradead.org,
        Robin Murphy <robin.murphy@arm.com>,
        Christoph Hellwig <hch@lst.de>,
        Drew Fustini <dfustini@baylibre.com>
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On Wed, Oct 4, 2023 at 5:21 PM Jisheng Zhang <jszhang@kernel.org> wrote:
> Drew found "CONFIG_DMA_GLOBAL_POOL=y causes ADMA buffer alloc to fail"
> the log looks like:
> [    3.741083] mmc0: Unable to allocate ADMA buffers - falling back to standard DMA
>
> The logic is: generic riscv defconfig selects ARCH_RENESAS then
> ARCH_R9A07G043 which selects DMA_GLOBAL_POOL, which assumes all
> non-dma-coherent riscv platforms have a dma global pool, this assumption
> seems not correct. And I believe DMA_GLOBAL_POOL should not be
> selected by ARCH_SOCFAMILIY, instead, only ARCH under some specific
> conditions can select it globaly, for example NOMMU ARM and so on,
> because it's designed for special cases such as "nommu cases where
> non-cacheable memory lives in a fixed place in the physical address
> map" as pointed out by Robin.
>
> Fix the issue by making ARCH_R9A07G043 (riscv version) depend on
> NONPORTABLE, thus generic defconfig won't select ARCH_R9A07G043 by
> default. And even for random config case, there will be less debug
> effort once we see NONPORTABLE is enabled.
>
> Reported-by: Drew Fustini <dfustini@baylibre.com>
> Closes: https://lore.kernel.org/linux-riscv/ZRuamJuShOnvP1pr@x1/
> Fixes: 484861e09f3e ("soc: renesas: Kconfig: Select the required configs for RZ/Five SoC")
> Signed-off-by: Jisheng Zhang <jszhang@kernel.org>

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
I guess this is the right thing to do until a better solution is found.
I.e. will queue in renesas-fixes for v6.6.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds