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 07CE230F7FF; Fri, 10 Jul 2026 10:36:01 +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=1783679763; cv=none; b=Bnj0Td+97Jf7FbgDMsMFUVRp08sgA2aSVHpYNxJGlv7yGgjy34U9tg0KeICm/xhK+l0Od3InyE861KH+C/qFmfMktzs1Cp30974P6YJiiUzUESM/d1FipO+/zOd8NeDyKtWoaD0IF8oNRoLFXvZhAAOVBy6/SHrkNSbVtlEeLVI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783679763; c=relaxed/simple; bh=3vcjY2oxw4SFIwjdVT0NU2H1M1Li/bHdUJVTc/OTiD4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=qvyS+zrrdmdDfsDFsOkIjpWkPKz06DQY7tS/EvdvdCUn8w+a+h87QVtHJYJgZpUUN27/Ls06eHrYglPQiuE+KpqQgAykGHSx+RcDDgvBWG3fNMUT+wrrRBxFO1rBAtuJ39wP3gJAfmiuPIhXfwaYfbqZ2z3o6IlNuhkxZ5Sv7o0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=G5dZYInk; 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="G5dZYInk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1F1DC1F000E9; Fri, 10 Jul 2026 10:35:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783679761; bh=prNlqSEvzCFjtktGE6ai2RnqxB/VdJvJpEgmZTwnQJc=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=G5dZYInkT5O1bzF5hs4RyapFu+5B2hpxe14HweSpSHXEBZW6gZc4ksYSvuf3KVlfB HNIiXK9ZDPBQx/dhaSISQnc1+MQg+K65msa9qRbIUqz37QQXFoT3tc1Z5nWTyBSNhR I5FBdvragiLa2gNMSg4w7vePainRWpbuYIQHzMWD5XkkNG2UJN4MC6WBfawAoUyZQs tp4JSCdnRqGCLAFYLH2e4rnzUlI4X/IDbpXTWLL26h7rarmSqAR20P9pboYcn3IuTS KOBH1pS/kpYR4C+wpsmgjpVeplI6zw8FlBNa2mu6Zloenuz5qeuo91p+A4X8pmafYH l7tkFYXWR5KzA== Message-ID: Date: Fri, 10 Jul 2026 11:35:57 +0100 Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 00/11] : media: iris: Migrate iommus to iris sub nodes To: Vikash Garodia , Dikshita Agarwal , Abhinav Kumar , Mauro Carvalho Chehab , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Bjorn Andersson , Konrad Dybcio Cc: linux-media@vger.kernel.org, linux-arm-msm@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, Vishnu Reddy References: <7GAZnP6jPoRrcDnaVzeaB98cONLhtvbiEXV1yD5MJJrA9pCnC9lmlSiCGA8vlDezSXADjmFiqo3ZdClO5SxCFA==@protonmail.internalid> <20260709-vpu_iommu_iova_handling-v1-0-72bb62cb2dfd@oss.qualcomm.com> From: Bryan O'Donoghue Content-Language: en-US Autocrypt: addr=bod@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 09/07/2026 13:35, Vikash Garodia wrote: > Mapping a stream outside its expected range can cause unintended > behavior, including device crashes, as reported at: > https://gitlab.freedesktop.org/drm/msm/-/work_items/100 > > Daniel, who reported the crash issue, have also raised a patch to workaround > the issue. While the patch partially handles the limitation, it is inefficient > in a way that it keep iris hardwares away from using the 600MB address space > for all the different streams. > > To address this limitation, the subset of stream/s are now represented as > sub nodes, so that they can be associated to the respective addressable > range. > In the past, this limitation was tried with iommu-map approach, with iris > driver dynamically creating the devices. The approach was later concluded > as an hack to avoid having sub nodes. It was discussed in detail in the > discussionhttps://lore.kernel.org/all/c7b956a9-d3e8-4e18-b780-5d08f5cd2ca1@kernel.org/ > > It was agreed by maintainers to proceed with sub node approach to address > the VPU hardware limitation. What's the addressable range with sub-nodes ? The original problem you were trying to solve was the total addressable size - this other problem here segmenting the linear allocation space is adjacent but not the same thing. Without digging through all of the patches here - my question is does the original sub-node addressable space problem get resolved in your proposal here ? --- bod