Re: [PATCH] soc: renesas: make ARCH_R9A07G043 (riscv version) depend on NONPORTABLE

From: Robin Murphy <robin.murphy@arm.com>
To: Jisheng Zhang <jszhang@kernel.org>,
	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>
Cc: linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-riscv@lists.infradead.org, Christoph Hellwig <hch@lst.de>,
	Drew Fustini <dfustini@baylibre.com>
Subject: Re: [PATCH] soc: renesas: make ARCH_R9A07G043 (riscv version) depend on NONPORTABLE
Date: Wed, 4 Oct 2023 16:27:46 +0100	[thread overview]
Message-ID: <c4438f24-fe87-bf22-183b-f53376e950db@arm.com> (raw)
In-Reply-To: <20231004150856.2540-1-jszhang@kernel.org>

On 04/10/2023 4:08 pm, 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.

FWIW,

Reviewed-by: Robin Murphy <robin.murphy@arm.com>

> 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