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Fri, 10 Jul 2026 06:36:42 -0700 (PDT) X-Received: by 2002:a05:6a20:3d20:b0:3b4:e4f0:94e1 with SMTP id adf61e73a8af0-3c0bd0f9dbemr14518495637.39.1783690602425; Fri, 10 Jul 2026 06:36:42 -0700 (PDT) Received: from [10.204.101.214] ([202.46.23.25]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-13b659d8da9sm74501495c88.14.2026.07.10.06.36.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 10 Jul 2026 06:36:41 -0700 (PDT) Message-ID: Date: Fri, 10 Jul 2026 19:06:35 +0530 Precedence: bulk X-Mailing-List: devicetree@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: Bryan O'Donoghue , 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> Content-Language: en-US From: Vikash Garodia In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Proofpoint-ORIG-GUID: DUOAsYJW7Kk8r6vaDXHHq3_l5Op68S1b X-Authority-Analysis: v=2.4 cv=PLg/P/qC c=1 sm=1 tr=0 ts=6a50f56b cx=c_pps a=Oh5Dbbf/trHjhBongsHeRQ==:117 a=ZePRamnt/+rB5gQjfz0u9A==:17 a=IkcTkHD0fZMA:10 a=RAioF0-LDSMA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=ZpdpYltYx_vBUK5n70dp:22 a=e5mUnYsNAAAA:8 a=VwQbUJbxAAAA:8 a=5i2VpEqXucwHfqzRn4MA:9 a=QEXdDO2ut3YA:10 a=_Vgx9l1VpLgwpw_dHYaR:22 a=Vxmtnl_E_bksehYqCbjh:22 X-Proofpoint-Spam-Info: AW1haW4tMjYwNzEwMDEzNSBTYWx0ZWRfX8oIajsIyQNd+ SnFtU0Wagud2d1cWEvw7pyr57cDLRItDbJIeIi+VBy64svvrcl4VsYbXwz4+7uuxJu8jENtDLiu LkbSyeSj0T6Kvfkj4iQH9JB43m0GBZo= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNzEwMDEzNSBTYWx0ZWRfXwRhpNFJiEhGd h4W8XTgA+5JYKi9d5apEDDogf93q7ZrFF4KgYJOW3c24et6z9h45Fqbl7yFS9Cz+SCo3lalHj50 wGdaTrrdMZgVviQ5I04hVoRUsyLQD2R8K+Dh16yOkHhbIcr2yTCmrkDVqTcndoOgjM6oiAfv0mr 4N3Ynvb37E2FdS1Rtbu+cFRCftAZf+exwhvHVCiX+YaI3ejAKryHcXDMZXGjMzxshWyNUZsWjBV qojYTXzkCTQFOQgjDov72UCAiCHs7vBohyZBw2iC8Y0vv9mRXJUpBS3n3/u+Z9FxzikoPKxMosM ubffVjtGR+0Xhk0r07pVgkxP3JEaPej98eeZGEK9XmH3BpOuQZSW3JXcNfbrJse67v383kyVWoF ssnklzZT9Kn4Ie+mGqxTs/gHw01C6yMx07wJ0jB8ly6sCHjCIlYdkK5htfBnG3KpbAWb3P/ACsU SF79Fz5RoKlr848DPXw== X-Proofpoint-GUID: DUOAsYJW7Kk8r6vaDXHHq3_l5Op68S1b X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-07-10_03,2026-07-10_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 phishscore=0 suspectscore=0 clxscore=1015 priorityscore=1501 impostorscore=0 malwarescore=0 adultscore=0 bulkscore=0 spamscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2607100135 On 7/10/2026 4:05 PM, Bryan O'Donoghue wrote: > 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 ? The proposal solves both the problem we have so far - total addressable size as well as which segment (or range) in that is _not_ addressable. Regards, Vikash > > --- > bod