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

From: Benjamin Gaignard <benjamin.gaignard@collabora.com>
To: Diederik de Haas <didi.debian@cknow.org>
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,
	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 15:48:14 +0200	[thread overview]
Message-ID: <2596fddc-aa76-4234-b182-1159c14b7cf8@collabora.com> (raw)
In-Reply-To: <DAOTVW4YEC5Q.STXG6APE0YGN@cknow.org>

Le 17/06/2025 à 15:04, Diederik de Haas a écrit :
> 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.

Only one hardware block exists on rk3588 and it can only be used
by Verisilicon AV1 codec.

>
>> 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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