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Tue, 3 Mar 2026 00:40:06 -0800 From: Akhil R To: CC: , , , , , , , , , , , , , Subject: Re: [PATCH v2 1/9] dt-bindings: dma: nvidia,tegra186-gpc-dma: Add iommu-map property Date: Tue, 3 Mar 2026 14:10:05 +0530 Message-ID: <20260303084005.57114-1-akhilrajeev@nvidia.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260303-famous-fearless-asp-1240cb@quoll> References: <20260303-famous-fearless-asp-1240cb@quoll> Precedence: bulk X-Mailing-List: linux-tegra@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain X-NV-OnPremToCloud: ExternallySecured X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: CH2PEPF0000013F:EE_|PH7PR12MB7988:EE_ X-MS-Office365-Filtering-Correlation-Id: 3986aaa2-a2ae-4abb-6722-08de7900849b X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|82310400026|7416014|376014|1800799024|36860700013; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:216.228.118.232;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc7edge1.nvidia.com;CAT:NONE;SFS:(13230040)(82310400026)(7416014)(376014)(1800799024)(36860700013);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: MsD+McB385vxu8tbIGwwTnuM7Fv4IFuqbHKmhnstUd+vTmrJBvicaJdFeCvOtAh1Lut0qPKjphEv/KzlEVGCdC/oA9VFIGf2wmoagQlvrjcVsHOJw5kxTmHSIkJugQYGCzp+aEgdd1U+3Bo4FM5HmmlpkNaExaqcgQtI5DFOYkaQIlRTiNgFkjSn5yPuuJuOqd2T5WQZy8uHwDNHDgFm7x2VDmvkeXM5dz0Wed7l3ixzrReIPYW9nmk9hiwwyfvdQDdJbCulYCX0WK16/a8tpz09NBv0tukLboGJwOU34I2M0pr/cl3zRuKN5FOKOiUeA0rPY52Su8x5736eU4IkVXRQPflHvUmDvCxrudrg4mGRNnPF/KxplWfQOiMl3ZZZYuQK+zcEqgTonZ7m1V507zps3ucaUIjaAJAnpy+pFO6Dtovmmjdotf3qLilR8djs X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Mar 2026 08:40:26.3257 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 3986aaa2-a2ae-4abb-6722-08de7900849b X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.118.232];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: CH2PEPF0000013F.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH7PR12MB7988 On Tue, 3 Mar 2026 07:39:58 +0100 Krzysztof Kozlowski wrote: > On Mon, Mar 02, 2026 at 06:02:31PM +0530, Akhil R wrote: >> Add iommu-map property to specify separate stream IDs for each DMA >> channel. This enables each channel to be in its own IOMMU domain, >> keeping memory isolated from other devices sharing the same DMA >> controller. >> >> Signed-off-by: Akhil R >> --- >> .../devicetree/bindings/dma/nvidia,tegra186-gpc-dma.yaml | 5 +++++ >> 1 file changed, 5 insertions(+) >> >> diff --git a/Documentation/devicetree/bindings/dma/nvidia,tegra186-gpc-dma.yaml b/Documentation/devicetree/bindings/dma/nvidia,tegra186-gpc-dma.yaml >> index 0dabe9bbb219..1e7b5ddd4658 100644 >> --- a/Documentation/devicetree/bindings/dma/nvidia,tegra186-gpc-dma.yaml >> +++ b/Documentation/devicetree/bindings/dma/nvidia,tegra186-gpc-dma.yaml >> @@ -14,6 +14,7 @@ description: | >> maintainers: >> - Jon Hunter >> - Rajesh Gumasta >> + - Akhil R >> >> allOf: >> - $ref: dma-controller.yaml# >> @@ -51,6 +52,10 @@ properties: >> iommus: >> maxItems: 1 >> >> + iommu-map: >> + minItems: 1 >> + maxItems: 32 > > Why is this flexible? If it is, means usually items are distinctive, so > I would expect defining/listing them. If they are not distinctive, > commit msg is incorrect. If the list is as simple as 1-to-1 channel > mapping, just add it in the description how they are ordered. Yes, it is a 1-to-1 channel mapping to an IOMMU ID. The intent of making it flexible is to allow non-consecutive IOMMU ID assignments as well. This is particularly needed in virtualised environments where the hypervisor may reserve certain stream IDs, and the guest VM can map only the permitted ones. Shall I add a description here mentioning this use-case? > >> + >> dma-coherent: true >> >> dma-channel-mask: >> -- >> 2.50.1 >