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Tue, 28 Oct 2025 06:08:21 -0700 From: Akhil R To: CC: , , , , , , , , , , , , Subject: Re: [PATCH v9 1/4] i2c: tegra: Do not configure DMA if not supported Date: Tue, 28 Oct 2025 18:38:20 +0530 Message-ID: <20251028130820.52188-1-akhilrajeev@nvidia.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-i2c@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: CO1PEPF000044F5:EE_|CH1PPFC908D89D1:EE_ X-MS-Office365-Filtering-Correlation-Id: 0c71673c-c9ac-44e6-d2a8-08de16231f85 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700013|7416014|1800799024|376014|82310400026; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?7iGIOIxQKfxP/77zYH9r87Oodrcf8BPJ8c9j8eWM0eJI8rWNCnOErGhwJQL0?= =?us-ascii?Q?uDUq+96YbomJjfy3/5H8FnxIajRuEhnLJvHaJhlhxhhmp8VehC0qWDbriz7V?= =?us-ascii?Q?aZ9kDhMgKTiVPJWu0fJ0XDcbj2sUdycU7tR1ZPqJ99V2zVPLxWWAuW0FkT/6?= =?us-ascii?Q?ogS5Ml+mVfO9EZKZvTHphzamcJw+PHxEb2Oh64A32C3f5LrZAKc86YZ5Lxmy?= =?us-ascii?Q?tu2GDTRgK1EAGt6S5MKE+WN5Z2/15qy/EiUS19hdu8Vi88c4idt6syxXlqvT?= =?us-ascii?Q?VD4Epd2b+sL+3cIqRCLxIH9LmaZHEhEMC9pAniRm3fEWPrqa8ndMVbcaMkSS?= =?us-ascii?Q?AwPJQrTzFfSbWFqrEs3r0QI+CceWfekQ/o+q9HI7BXuSzPjPJpqAFA0ybtrA?= =?us-ascii?Q?H4NK8Ji3kUZIUa6GtLabolkRkGXl78nXKFNearQQJ/Z0yFMqDb1VYO6xEQFI?= =?us-ascii?Q?uuVyfi+ja/oZ7eDIahckO4SsNibRN3iEwocZHMRuzIh5RhoLKaDTek7BUI9k?= =?us-ascii?Q?uyo0w/rpbJV3ZKmy3DupHcfy4hRHwtP7NDW37e5/QSEE/OK0akrKFlIkPdPQ?= =?us-ascii?Q?fou9cF0E6FhvbkuXvDuk+GzoKOrlzA/zmeEm9SSHt00ew8Vu4piP+OgJSJcp?= =?us-ascii?Q?oRdkLslD8RovQ1W8nwOja8bgf6gVRcCPqG8vn6LHeHm1eME+IDVu8qjM45JM?= =?us-ascii?Q?gTqEQCyAYFtq+pZiLo5BBlVCMo/4hmyYbGwNTSKjc+/GUEul9h12Ycep6wKN?= =?us-ascii?Q?/2SlK51YGT9MXIXNJJ2UmSFfy45k2mTyEnQ86suW1iiOxnWftpdNGfYsgEfX?= =?us-ascii?Q?8sT1VLfkgfQaD+75EGeaPgvtg9+gt9Tjg8o5Qdf2WaoMQ5btXcDaXXgjRF8y?= =?us-ascii?Q?/W5JeLlpOhX/YNF0JCawmIszMuLqGc1EwW+G9YejQR8Xt4a9cSTA8XZIErVm?= =?us-ascii?Q?ZBkz6xqxLj0lKyudFBZnCWinBU7Ysm6c3OC2cLKTuSA9+co+SgzpnXEzU1+C?= =?us-ascii?Q?dIw1WvRVUX+UJV0v561UNdBU0TjLWygzPsereUp07dhtxGEZjg72SaWqJVyw?= =?us-ascii?Q?imW4rotGZOEwPuFg1cUl5E501elmBxnWIGe3Ab2Pz794RHEyRQy4H0cJV7M8?= =?us-ascii?Q?NYbimVPqjUDeuHIiAznuUbN7Y3RY4zaKXafHeBGlVNxtHzDzSxj+iE6t7iIm?= =?us-ascii?Q?95HDKGrJe7wRhBnvahQdN9LPnl5aXgXh1csSeEtNyGvZ/TCPFgM3hS39Sd4E?= =?us-ascii?Q?h+FyXOplfJ/0bio8Vrjv72fKn7UCUmTRGgiIadvOySNgt5V/acZcvaeDCF/R?= =?us-ascii?Q?roCtpSrYfmAOfa0PAIQEcYOOjusIzFE442kVYXBguj69zPQioBH0yBVrAsQg?= =?us-ascii?Q?3VKAl8XxqC+SRFY21a7xQVHmmnzbQFDBKO5Q24MF4R6Sj1P2+7tG06QsbQnw?= =?us-ascii?Q?ctxU4jAyIVu26KdVYfuIXC+5lEPCMppLTZxKdaVsERzFC1jlMZNJslr2Aa3M?= =?us-ascii?Q?6fThjndntq02/o/k6+JcEIOeWB173QBb40ei6ZcY1hbX4/9dRPS4GVfqettp?= =?us-ascii?Q?SlRfMZo8dWrNr4EMQRg=3D?= X-Forefront-Antispam-Report: CIP:216.228.117.161;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge2.nvidia.com;CAT:NONE;SFS:(13230040)(36860700013)(7416014)(1800799024)(376014)(82310400026);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 Oct 2025 13:08:44.0680 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 0c71673c-c9ac-44e6-d2a8-08de16231f85 X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.161];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: CO1PEPF000044F5.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH1PPFC908D89D1 On Tue, 28 Oct 2025 10:41:54 +0000 Jon Hunter wrote: > On 28/10/2025 10:00, Akhil R wrote: >> On Fri, 24 Oct 2025 16:20:09 +0100, Jon Hunter wrote: >>> On 01/10/2025 07:47, Kartik Rajput wrote: ... >>>> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c >>>> index e533460bccc3..aa7c0d8c0941 100644 >>>> --- a/drivers/i2c/busses/i2c-tegra.c >>>> +++ b/drivers/i2c/busses/i2c-tegra.c >>>> @@ -449,6 +449,11 @@ static int tegra_i2c_init_dma(struct tegra_i2c_dev *i2c_dev) >>>> if (IS_VI(i2c_dev)) >>>> return 0; >>>> >>>> + if (!of_property_present(i2c_dev->dev->of_node, "dmas")) { >>>> + dev_dbg(i2c_dev->dev, "DMA not available, falling back to PIO\n"); >>>> + return 0; >>>> + } >>>> + >>>> if (i2c_dev->hw->has_apb_dma) { >>>> if (!IS_ENABLED(CONFIG_TEGRA20_APB_DMA)) { >>>> dev_dbg(i2c_dev->dev, "APB DMA support not enabled\n"); >>> >>> What about ACPI based devices? >> >> The of_ function returns false if using ACPI. Since these DMA drivers does >> not support ACPI enumeration currently, we would not require to proceed >> further anyway. But if required we can add an additional check with >> acpi_dma_supported() or similar. Do you suggest adding a check for ACPI? > > I was just wondering if it is better to use fwnode_property_present() > instead. I think ACPI does not use 'dmas' property to connect a DMA resource. It uses FixedDMA or something similar. It may not be helpful to use fwnode_*() or device_*() check here in that case. Regards, Akhil