From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3C06F40F743; Fri, 25 Sep 2026 18:47:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790362048; cv=none; b=aBPNIbk4V0AUttU4a6RP0c+wQjICv8eusCMCjaoXjTkG4r/GXibtGssovdJcgiHmY9ypTfEiyCdwchEX1o6Mmoi6MeA9K/wRHTJwZaHbyupnof+h8N3wKbRSZMbwwyFiLbI4KOjVA3+ygIkdecbMMl9YgEz92yp+x3RZnI3Q79w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790362048; c=relaxed/simple; bh=uUthPR+U6yJR5NV/uG+qPvhxGRWz9fJMEqlA47VF0KI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=qKpY2xr/lFhZrIdq1d06I3oE6lMq6EryDqgMj9N5Yded/YMWsHF3waR8lxi3qu1aKSiR42/umjbPNdWZvmAb+AHLRVFcLBLgU5D6V06rab/bNr4CVFhdb1hwWiRNjjqHOO+lZ2VuzZdhWgt7ZIfPgFbqTa4+VV4eYV73yzIYS6Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=U6GZWdu/; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="U6GZWdu/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BC66F1F00893; Fri, 25 Sep 2026 18:47:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790362047; bh=4Lp1TuV2qHhnQwElR/zZ3qZXtrPpXya5hITUNnZh9oo=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=U6GZWdu/kbN3OPRr+vVywjONhy+gTbyF89gpBMfOdbbDEzGAGQOQW7fDRup0P7smB F0Q53CVL/jHBG2o4FzW2W6vGeVCPf32Tzge6bx+zOA6F3d1cMlBRnVrocxkKJHyCG6 gNurIhfITbC9QC94hTQeMPGi00AZBi5894BvDl5MC8cbCw+kzo95CVnFDX/vKtR0iV 84Eac/SHOP6HW97fnS0iwWvRXFdo6UHJuKNdQ9X0z7KBbB7IxNAiHW72bh8E6Kd4iv MUWD2tvt65xDpSZVeeB0mvWz0jG+ocM3Y9SDjM+eD2Pkmw0Tf+Lpk8FPMEKdPQO8SP u0VY3f81dFEog== Message-ID: <08bca12d-1587-4b9d-9f60-2e1057705ba0@kernel.org> Date: Fri, 25 Sep 2026 20:47:15 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v4 01/13] dt-bindings: media: qcom,venus: Add context bank subnodes to common schema To: Vikash Garodia , Dikshita Agarwal , Abhinav Kumar , Bryan O'Donoghue , Mauro Carvalho Chehab , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Bjorn Andersson , Konrad Dybcio , Stanimir Varbanov , Neil Armstrong , Dmitry Baryshkov , Bryan O'Donoghue , Stephan Gerhold , "Joerg Roedel (AMD)" , Will Deacon , Robin Murphy , Abel Vesa Cc: linux-media@vger.kernel.org, linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Konrad Dybcio , iommu@lists.linux.dev References: <20260914-vpu_iommu_iova_handling-v4-0-9b9074a73c41@oss.qualcomm.com> <20260914-vpu_iommu_iova_handling-v4-1-9b9074a73c41@oss.qualcomm.com> From: Krzysztof Kozlowski Content-Language: en-US Autocrypt: addr=krzk@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 13/09/2026 20:49, Vikash Garodia wrote: > The VPU issues DMA through several SMMU streams, and the hardware does > not give every stream the same addressable range. The non-pixel stream > cannot address the low 600MB of IOVA space, while the pixel stream can > address the full range: > +-----------------------------------------------------------+ > | non-pixel stream addressable range (600 MB - 3.5 GB) | > | 0x25800000 - 0xe0000000 | > +-----------------------------------------------------------+ > | pixel stream addressable range (0 - 3.5 GB) | > | 0x00000000 - 0xe0000000 | > +-----------------------------------------------------------+ > A single "iommus" property on the video-codec node puts every stream in > one IOMMU domain sharing one IOVA allocator, so nothing restricts a > non-pixel buffer to avoid 0 to 600MB. Once an allocation lands below > that boundary the hardware faults, which shows up as unhandled SMMU page > faults and spontaneous reboots: > https://gitlab.freedesktop.org/drm/msm/-/work_items/100 > > Given that the address range restriction is for specific VPU stream, it > should be ideally be moved to that stream. To achieve the same, a subset > of streams is now represented as subnodes, so that each can be > associated with its respective addressable range. The design was > discussed and agreed by mainatiners here > https://lore.kernel.org/all/c7b956a9-d3e8-4e18-b780-5d08f5cd2ca1@kernel.org > > In the past, this limitation was addressed with an iommu-map approach, > with the iris driver dynamically creating the devices. That approach was > later concluded to be a hack to avoid having subnodes, and was NAKed by > the iommu maintainers. It was discussed in detail here: > https://lore.kernel.org/all/c7b956a9-d3e8-4e18-b780-5d08f5cd2ca1@kernel.org/ Reviewed-by: Krzysztof Kozlowski Best regards, Krzysztof