Re: [PATCH 3/5] iommu: Add verisilicon IOMMU driver

From: "Diederik de Haas" <didi.debian@cknow.org>
To: "Benjamin Gaignard" <benjamin.gaignard@collabora.com>
Cc: <joro@8bytes.org>, <will@kernel.org>, <robin.murphy@arm.com>,
	<robh@kernel.org>, <krzk+dt@kernel.org>, <conor+dt@kernel.org>,
	<heiko@sntech.de>, <nicolas.dufresne@collabora.com>,
	<p.zabel@pengutronix.de>, <mchehab@kernel.org>, <joro@8bytes.org>,
	<iommu@lists.linux.dev>, <devicetree@vger.kernel.org>,
	<linux-kernel@vger.kernel.org>,
	<linux-arm-kernel@lists.infradead.org>,
	<linux-rockchip@lists.infradead.org>,
	<linux-media@vger.kernel.org>, <kernel@collabora.com>
Subject: Re: [PATCH 3/5] iommu: Add verisilicon IOMMU driver
Date: Tue, 17 Jun 2025 15:04:44 +0200	[thread overview]
Message-ID: <DAOTVW4YEC5Q.STXG6APE0YGN@cknow.org> (raw)
In-Reply-To: <20250616145607.116639-4-benjamin.gaignard@collabora.com>

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Hi,

On Mon Jun 16, 2025 at 4:55 PM CEST, Benjamin Gaignard wrote:
> Verisilicon IOMMU hardware block can be found in combination

Can there be only 1 hardware block or is multiple possible?
If only 1, then I'd start with "The Verisilicon ...".
If more then one, then I'd use "blocks".

> with hardware video codecs (encoders or decoders) on
> different SoCs.

This makes it sound like it can also be used with non-Verisilicon codecs
and based on the DT binding description, I get the _impression_ that
that is not the case?
But it's actually not clear to me if that's the case or not.

> Enable it will allows to use non contiguous memory

"Enabling it will allow us to use non ..." or "Enable it to allow [the]
use of non ..." or "Enabling allows the use of non ..."

> allocators for Verisilicon video codecs.

And the wrapping of the whole commit message is not following the
standards.

> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
> ---
>  drivers/iommu/Kconfig     |   8 +
>  drivers/iommu/Makefile    |   1 +
>  drivers/iommu/vsi-iommu.c | 900 ++++++++++++++++++++++++++++++++++++++
>  3 files changed, 909 insertions(+)
>  create mode 100644 drivers/iommu/vsi-iommu.c
>
> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
> index 0a33d995d15d..4cf4504dcc25 100644
> --- a/drivers/iommu/Kconfig
> +++ b/drivers/iommu/Kconfig
> @@ -383,4 +383,12 @@ config SPRD_IOMMU
>  
>  	  Say Y here if you want to use the multimedia devices listed above.
>  
> +config VSI_IOMMU
> +	bool "Verisilicon IOMMU Support"
> +	depends on ARM64
> +	select IOMMU_API
> +	select ARM_DMA_USE_IOMMU
> +	help
> +	  Support for IOMMUs used by Verisilicon video decoders.
> +
>  endif # IOMMU_SUPPORT
> diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile
> index 355294fa9033..68aeff31af8b 100644
> --- a/drivers/iommu/Makefile
> +++ b/drivers/iommu/Makefile
> @@ -34,3 +34,4 @@ obj-$(CONFIG_IOMMU_SVA) += iommu-sva.o
>  obj-$(CONFIG_IOMMU_IOPF) += io-pgfault.o
>  obj-$(CONFIG_SPRD_IOMMU) += sprd-iommu.o
>  obj-$(CONFIG_APPLE_DART) += apple-dart.o
> +obj-$(CONFIG_VSI_IOMMU) += vsi-iommu.o
> diff --git a/drivers/iommu/vsi-iommu.c b/drivers/iommu/vsi-iommu.c
> new file mode 100644
> index 000000000000..f2fa1197916c
> --- /dev/null
> +++ b/drivers/iommu/vsi-iommu.c
> @@ -0,0 +1,900 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +

No copyright statement? (or an informational header block?)

Cheers,
  Diederik

> +#include <linux/clk.h>
> + <snip>

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