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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Proofpoint-ORIG-GUID: Nm38B2tK1LPQOv8ySliE66fYNnY2lbLA X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTMwMDA0MSBTYWx0ZWRfXxvvzPewj/7Qp DvjS8mpJFLtBlxfxuoK6nI6zgjiSzqzAqKg6r+9LmSPbLrBBbpc9JIIpZKcz0XauwTX1JtmZj5v 0PirIgERJExbAaOcHVG9SfRSKNRY7fbhyhrfBkAw4nalRRyF5AQJfRjFbJHz1hc+iy0w64YLD1X 2nmpiFBS7VEmr6AMRXnlEG3q5f06bm2vAqRKIhdk1Kf8W0meVR+zzVewlCVmXV9pA59m8slJj+6 49+9xph5mGHkix6C841iYyUV5IegpOtFvdv5E64jtT6lOlrcA/BbgwM0dh0R/q82b99vvek2NvH M8NBRsEsehi2Vgz8deJCgiJ/obAbpII4aaqo8rF6GylZ5xDgwkpKCSJgCSK/bijAm24ucgl392c ha0nNsE1U/jqTQIQdJ6Lq3HLDlsk3pWDEUezyI5r3SVxt8uiKCyxWzEf+o+dO/Il6BWtat52Z9e 0QMDy434ZhuvKtfI11g== X-Proofpoint-Spam-Info: AW1haW4tMjYwOTMwMDA0MSBTYWx0ZWRfX1BLL5KNuPe0I 2e2B9PtTj00/m6I4wcL6sgUjNUQzvoeJV3ab2lvx5lnWK/OfGqmey+Hn6jd8FtUwQ4E2P2nBfOH HLPbAxEl+2qhPK92GLmWjohHRPvjOfg= X-Proofpoint-GUID: Nm38B2tK1LPQOv8ySliE66fYNnY2lbLA X-Authority-Analysis: v=2.4 cv=fqxJ914f c=1 sm=1 tr=0 ts=6abce55c cx=c_pps a=WeENfcodrlLV9YRTxbY/uA==:117 a=PRfkaYvzSr8QmIIGAkY2Sg==:17 a=IkcTkHD0fZMA:10 a=VdqzKS8jKosA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=_glEPmIy2e8OvE2BGh3C:22 a=e5mUnYsNAAAA:8 a=VwQbUJbxAAAA:8 a=EUspDBNiAAAA:8 a=G2U8quZLHxfXJRKprjwA:9 a=QEXdDO2ut3YA:10 a=kacYvNCVWA4VmyqE58fU:22 a=Vxmtnl_E_bksehYqCbjh:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-30_01,2026-09-21_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 clxscore=1015 impostorscore=0 malwarescore=0 suspectscore=0 spamscore=0 bulkscore=0 priorityscore=1501 lowpriorityscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609300041 On 9/26/26 8:34 AM, 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/ > > The video-codec node includes address-cells, size-cells and dma-ranges > to declare 1:1 mapping for DMA translation to the parent. > > Co-developed-by: Vishnu Reddy > Signed-off-by: Vishnu Reddy > Signed-off-by: Vikash Garodia > --- Reviewed-by: Konrad Dybcio Konrad