From: Robin Murphy <robin.murphy@arm.com>
To: Samuel Holland <samuel@sholland.org>,
Joerg Roedel <joro@8bytes.org>, Will Deacon <will@kernel.org>,
iommu@lists.linux-foundation.org
Cc: devicetree@vger.kernel.org, Heiko Stuebner <heiko@sntech.de>,
linux-kernel@vger.kernel.org,
Jernej Skrabec <jernej.skrabec@gmail.com>,
Chen-Yu Tsai <wens@csie.org>, Rob Herring <robh+dt@kernel.org>,
Palmer Dabbelt <palmer@dabbelt.com>,
Maxime Ripard <mripard@kernel.org>,
Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
Philipp Zabel <p.zabel@pengutronix.de>,
linux-riscv@lists.infradead.org, linux-sunxi@lists.linux.dev,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH 5/5] iommu/sun50i: Ensure the IOMMU can be used for DMA
Date: Thu, 28 Apr 2022 12:12:39 +0100 [thread overview]
Message-ID: <7b09e989-0aa1-a557-485e-572f69caf881@arm.com> (raw)
In-Reply-To: <20220428010401.11323-6-samuel@sholland.org>
On 2022-04-28 02:04, Samuel Holland wrote:
> So far, the driver has relied on arch/arm64/Kconfig to select IOMMU_DMA.
> Unsurprisingly, this does not work on RISC-V, so the driver must select
> IOMMU_DMA itself.
No, IOMMU_DMA should only be selected by the architecture code that's
also responsible for calling iommu_setup_dma_ops(). Without that, this
select will do nothing other than add some unused code to the kernel image.
I appreciate that the current state of the x86 IOMMU drivers being
tightly-coupled to the x86 arch code might be confusing (which reminds
me I'd totally forgotten about [1]). I'm about to start reworking the
whole area anyway, but for now please just follow the existing intent.
Thanks,
Robin.
[1]
https://lore.kernel.org/linux-iommu/9ba6f2e8568a3ff6a94fade66668d99705433c44.1631536879.git.robin.murphy@arm.com/
> Signed-off-by: Samuel Holland <samuel@sholland.org>
> ---
>
> drivers/iommu/Kconfig | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> index c79a0df090c0..70a0bfa6d907 100644
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -223,6 +223,7 @@ config SUN50I_IOMMU
> depends on ARCH_SUNXI || COMPILE_TEST
> select ARM_DMA_USE_IOMMU
> select IOMMU_API
> + select IOMMU_DMA
> help
> Support for the IOMMU introduced in the Allwinner H6 SoCs.
>
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next prev parent reply other threads:[~2022-04-28 11:12 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-28 1:03 [PATCH 0/5] iommu/sun50i: Allwinner D1 support Samuel Holland
2022-04-28 1:03 ` [PATCH 1/5] dt-bindings: iommu: sun50i: Add compatible for Allwinner D1 Samuel Holland
2022-04-28 7:19 ` Krzysztof Kozlowski
2022-04-28 1:03 ` [PATCH 2/5] iommu/sun50i: Support variants without an external reset Samuel Holland
2022-04-28 5:34 ` Jernej Škrabec
2022-04-28 7:43 ` Philipp Zabel
2022-04-28 1:03 ` [PATCH 3/5] iommu/sun50i: Ensure bypass is disabled Samuel Holland
2022-04-28 5:43 ` Jernej Škrabec
2022-04-28 1:03 ` [PATCH 4/5] iommu/sun50i: Add support for the D1 variant Samuel Holland
2022-04-28 5:34 ` Jernej Škrabec
2022-04-28 1:04 ` [PATCH 5/5] iommu/sun50i: Ensure the IOMMU can be used for DMA Samuel Holland
2022-04-28 5:35 ` Jernej Škrabec
2022-04-28 11:12 ` Robin Murphy [this message]
2022-04-28 5:45 ` [PATCH 0/5] iommu/sun50i: Allwinner D1 support Jernej Škrabec
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