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From: Robin Murphy <robin.murphy@arm.com>
To: Benjamin Gaignard <benjamin.gaignard@collabora.com>,
	Jason Gunthorpe <jgg@ziepe.ca>
Cc: joro@8bytes.org, will@kernel.org, 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 5/5] media: verisilicon: Flush IOMMU before decoding a frame
Date: Tue, 17 Jun 2025 17:04:57 +0100	[thread overview]
Message-ID: <77867c46-d868-4496-a1a3-45feb0bdd604@arm.com> (raw)
In-Reply-To: <30a48107-8e98-42dd-a5a7-9c87c9eb538d@collabora.com>

On 17/06/2025 5:01 pm, Benjamin Gaignard wrote:
> 
> Le 17/06/2025 à 17:58, Jason Gunthorpe a écrit :
>> On Mon, Jun 16, 2025 at 04:55:53PM +0200, Benjamin Gaignard wrote:
>>> Flush the IOMMU mapping before decoding a frame to ensure that all 
>>> memory
>>> translations are properly applied.
>>>
>>> Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
>>> ---
>>>   drivers/media/platform/verisilicon/hantro_drv.c | 11 +++++++++++
>>>   1 file changed, 11 insertions(+)
>> This is a really big red flag.
>>
>> iommu translations are supposed to be controlled by the iommu driver
>> and should be flushed as part of the iommu map/unmap flows. It should
>> never be necessary to do something like this.
> 
> I have redone tests without this patch and the decode is perform correctly.
> I will drop it in the next version.
> I think I have fix the reference frame management in the driver so it 
> becomes
> useless.

If it turns out the hardware does require a TLBI to guarantee new 
mappings are visible, though, then the correct way is to implement the 
iotlb_sync_map op.

Thanks,
Robin.

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      reply	other threads:[~2025-06-17 17:12 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-06-16 14:55 [PATCH 0/5] Add support for Verisilicon IOMMU used by media codec blocks Benjamin Gaignard
2025-06-16 14:55 ` [PATCH 1/5] dt-bindings: vendor-prefixes: Add Verisilicon Benjamin Gaignard
2025-06-16 15:15   ` Conor Dooley
2025-06-16 14:55 ` [PATCH 2/5] dt-bindings: iommu: verisilicon: Add binding for VSI IOMMU Benjamin Gaignard
2025-06-16 15:14   ` Conor Dooley
2025-06-16 15:30     ` Benjamin Gaignard
2025-06-16 15:42       ` Conor Dooley
2025-06-16 15:50         ` Benjamin Gaignard
2025-06-16 15:58           ` Conor Dooley
2025-06-16 16:06             ` Benjamin Gaignard
2025-06-16 21:19     ` Nicolas Dufresne
2025-06-16 14:55 ` [PATCH 3/5] iommu: Add verisilicon IOMMU driver Benjamin Gaignard
2025-06-17 13:04   ` Diederik de Haas
2025-06-17 13:48     ` Benjamin Gaignard
2025-06-17 16:32   ` Jason Gunthorpe
2025-06-18 12:04     ` Benjamin Gaignard
2025-06-18 13:27       ` Jason Gunthorpe
2025-06-18  4:53   ` kernel test robot
2025-06-16 14:55 ` [PATCH 4/5] arm64: dts: rockchip: Add verisilicon IOMMU node on RK3588 Benjamin Gaignard
2025-06-16 14:55 ` [PATCH 5/5] media: verisilicon: Flush IOMMU before decoding a frame Benjamin Gaignard
2025-06-17 15:58   ` Jason Gunthorpe
2025-06-17 16:01     ` Benjamin Gaignard
2025-06-17 16:04       ` Robin Murphy [this message]

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