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Date:   Wed, 4 Oct 2023 10:42:53 -0700
From:   Drew Fustini <dfustini@baylibre.com>
To:     Jisheng Zhang <jszhang@kernel.org>
Cc:     Geert Uytterhoeven <geert+renesas@glider.be>,
        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>
Subject: Re: [PATCH] soc: renesas: make ARCH_R9A07G043 (riscv version) depend
 on NONPORTABLE
Message-ID: <ZR2kHfUXmQ9jwQC9@x1>
References: <20231004150856.2540-1-jszhang@kernel.org>
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On Wed, Oct 04, 2023 at 11:08:56PM +0800, Jisheng Zhang 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>
> ---
>  drivers/soc/renesas/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/soc/renesas/Kconfig b/drivers/soc/renesas/Kconfig
> index 5a75ab64d1ed..12040ce116a5 100644
> --- a/drivers/soc/renesas/Kconfig
> +++ b/drivers/soc/renesas/Kconfig
> @@ -333,6 +333,7 @@ if RISCV
>  
>  config ARCH_R9A07G043
>  	bool "RISC-V Platform support for RZ/Five"
> +	depends on NONPORTABLE
>  	select ARCH_RZG2L
>  	select AX45MP_L2_CACHE if RISCV_DMA_NONCOHERENT
>  	select DMA_GLOBAL_POOL
> -- 
> 2.40.1
> 

Tested-by: Drew Fustini <dfustini@baylibre.com>

With this patch, I can use the defconfig and sdhci-of-dwcmshc driver is
able to use ADMA mode without needing to add shared-dma-pool to dts:

# zcat /proc/config.gz |grep DMA_GLOBAL_POOL
# dtc -I fs /sys/firmware/devicetree/base/ 2>/dev/null |grep pool
# dmesg |grep ADMA
[    3.910269] mmc0: SDHCI controller on ffe7080000.mmc [ffe7080000.mmc] using ADMA 64-bit


Thanks,
Drew