From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from DUZPR83CU001.outbound.protection.outlook.com (mail-northeuropeazon11022109.outbound.protection.outlook.com [52.101.66.109]) (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 BA0C533AD82; Mon, 5 Jan 2026 11:07:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=fail smtp.client-ip=52.101.66.109 ARC-Seal:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767611249; cv=fail; b=n7JXOFWgcbKndxzATFMwGAz213zmAvcVgKI+ESoetaCfUzU0088VfJ566TgcEY+TMXI0vaVLTOjDW1HzA23JJkPwHhcXW3EHqstrYphjtxAdltj5P9okXpOmeDiiF3Y8+fPJ9u0xEX9Ejdb9KyNKShBHhUpFBeMNr+1Gey/y5TI= ARC-Message-Signature:i=2; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767611249; c=relaxed/simple; bh=PCivtR9hxqt1cJNwFsmYTu/pmxsUh4m41mwmyKl/6Y4=; h=Message-ID:Date:Subject:To:Cc:References:From:In-Reply-To: Content-Type:MIME-Version; b=i7NUwt26jOreXJa+CeUYek5jHG2bXBpg4s33P/Iay/RQoKodRqMjHGspFFNYa8WPU9eXkB8Q5AxQ3zHkIfShjN26z4FV7OdM077uComkxyE8prP652LoWVpFsW1wirLhvRCcZwm0W2Exsptux5Vam79rjDtCMhkGxp+h7IpCw9g= ARC-Authentication-Results:i=2; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=vaisala.com; spf=pass smtp.mailfrom=vaisala.com; dkim=pass (2048-bit key) header.d=vaisala.com header.i=@vaisala.com header.b=d2ZN4rTu; arc=fail smtp.client-ip=52.101.66.109 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=vaisala.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=vaisala.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=vaisala.com header.i=@vaisala.com header.b="d2ZN4rTu" ARC-Seal: i=1; a=rsa-sha256; s=arcselector10001; d=microsoft.com; cv=none; b=zCvIVWoAunccuK7x3CctfLpS0Gr8ZHjElXzE62T8I+JlxYR1SlsKKXN5nU37+O0w1ASZRL6gLs+SYCFP4PmHRc66ebqLDQTiyyMNr1VBY+6YnePWgldBux0oFbPTOamOI4nSAUgcMJoWLLfQjEnJE9RGJbZbkTTHCQutO+eggbhWN2nrK4a3HzPzjPAwTU2++uMwcAV1nnXKaOxtLzD3Y06HaX4LdLfBS3S8OY1GwHT4T6JFoce4oNdhO7UUAH0FqCyJ/PUDUnBZGR25gWYyoN/A/ycxonFJ9LuF28JN7LdHJ8ikLiIgIEl4NZQmjDXjM6Y9gyPQ5PNNxUjj6SxPBg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector10001; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=3oKRxDyBw44b+EUc64Y/j0hICia9sDAdHsiKzjiZgWk=; b=AfYxUEj1dtt7cF9K2a4PBiTb/vZ8rJXVCRAYJ+gG7cCujWdaG8gA3l1lSVE8/EBuBpN6a3I+1t+V0oqK05afYQ+a6SgFS9j6IBm2bSkhxV8BZMpTLbY296H0ih8x6MscHaYXSrQItYQTXKubQbxOGpGQas9vwQkkA2/11ntCiFT/kccj64+/4Bies/wjVSoEDFf4hIOXOq+l0kxMMaLeegNjA+1NNSCdU3sWfYqN03IdWWOWyJRoUc2FNvMPddwztaQaAGUZVyF9jTSFpo9lc7i5dpaZdwN/W2tiBvQiL7M2Sfe2xMQ/FjFK6U7pawo4ULOEmWTzPbpXYf8K/YYKzA== ARC-Authentication-Results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=vaisala.com; dmarc=pass action=none header.from=vaisala.com; dkim=pass header.d=vaisala.com; arc=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=vaisala.com; s=selector1; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-SenderADCheck; bh=3oKRxDyBw44b+EUc64Y/j0hICia9sDAdHsiKzjiZgWk=; b=d2ZN4rTu5qhYjCudL0ASvZADxcX7t2eE+k6Ftj7jsTfcgdR9GQ5qnKfszXXb3vbf+Ptkl1Ex4kgw954DgZGzzm5uoEYiuZicJSzcXeoIcArggEZ+xvYU7BtnjW0p32F6kX7hniDuW3//hHwaGbDQDnHK1tqdZgzlBQ611ZfvHXnhCbUA/Dsl64djIcG90rNcoN3g29GSt6d4imwqRzeN+ZL1mYlaDkk9i+KqGLZ4kOlsRZxhQilQ09Y0wQ8ew/ss+/53L1e5LgI1K9HNOGSAAWaC7DbB2/zPmn1oOCIgduhyTxsvwCvIe4xXduJBs14DTfnazWPVn9aIvOlGwRlaBw== Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=vaisala.com; Received: from AMBPR06MB10365.eurprd06.prod.outlook.com (2603:10a6:20b:6f0::7) by AS5PR06MB8726.eurprd06.prod.outlook.com (2603:10a6:20b:654::20) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.9478.4; Mon, 5 Jan 2026 11:07:21 +0000 Received: from AMBPR06MB10365.eurprd06.prod.outlook.com ([fe80::4606:8e25:96e6:bede]) by AMBPR06MB10365.eurprd06.prod.outlook.com ([fe80::4606:8e25:96e6:bede%5]) with mapi id 15.20.9478.004; Mon, 5 Jan 2026 11:07:21 +0000 Message-ID: <356a75b0-dc3e-4d10-a827-1af3b4ab638f@vaisala.com> Date: Mon, 5 Jan 2026 13:06:13 +0200 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] iio: adc: ad9467: make iio backend optional To: Jonathan Cameron Cc: Michael Hennerich , Nuno Sa , Lars-Peter Clausen , David Lechner , Andy Shevchenko , linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org References: <20251216-b4-ad9467-optional-backend-v1-0-83e61531ef4d@vaisala.com> <20251216-b4-ad9467-optional-backend-v1-2-83e61531ef4d@vaisala.com> <20251221200014.29af7df8@jic23-huawei> Content-Language: en-US From: Tomas Melin In-Reply-To: <20251221200014.29af7df8@jic23-huawei> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-ClientProxiedBy: GVZP280CA0088.SWEP280.PROD.OUTLOOK.COM (2603:10a6:150:275::15) To AMBPR06MB10365.eurprd06.prod.outlook.com (2603:10a6:20b:6f0::7) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: AMBPR06MB10365:EE_|AS5PR06MB8726:EE_ X-MS-Office365-Filtering-Correlation-Id: 900e0c2d-cc1e-4d69-d616-08de4c4a98e4 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|366016|1800799024; X-Microsoft-Antispam-Message-Info: =?utf-8?B?N01JY0MxWlFhWVV2bU9QWmVoeU54M0FuQXFKcEkwZGlTR2VYMXRYOERRd2E4?= =?utf-8?B?S2s0NGk0VVdOMktIYVorRlRYRmlISHk3dS9oWjNUK2ljN1ZyNkNJQ0JoWUpQ?= =?utf-8?B?ZUIwNFlYUTJNaWpOMTdtSDQ2WmE1dmhBQXRjSHEyMEZwQ2RXK3dLVE94S0s3?= =?utf-8?B?aXBQc2krVWhyenU1MUJDS3N1T0pJUmM5TnM3SEgrbkVBV0pFek9KR0tEWHlS?= =?utf-8?B?UForeDRNQmZEcXZGQU1TWVR6WExmTjhGRnlUZm1FMUN3a0NvZEpjN2VubHpZ?= =?utf-8?B?eVRIL3JtRVF4WktWZjZIdjdscDNMb3FxZDZoQUlRdGg1OTFDZ0ljb05ZUXVj?= =?utf-8?B?eWJZTGRra0NaUlk0Z3dvVnI3dCsyVUE5OG1ySmZVWFJEL3ZITzZNM3dqcEZG?= =?utf-8?B?RVQ5QytScCtKNWtqTnFvQnZYWWhFZG5yWjgvUFRlaGFLQ280emQ4OS9ZcXJX?= =?utf-8?B?aGVoYmZYQVpia2trdXRwQW5DTkVhanFKL2NKS21udExGMHZuL3gwYjRUdG02?= =?utf-8?B?bFFNQUd6U2ZBc0RQVG5paW9ZMkJwRkhjVUR4aGlLcmkyYVNHd0tKa25kRDJt?= =?utf-8?B?KzRzaVFWWWdLMTcxYWNnNjN5SXJzakFEZ2EwRXhXK0EwZ1dBV21WcjhBempU?= =?utf-8?B?SVB6RWlCazd2YkNBNXF2eWNib1BHQ3J0Rk1ZNXIrR1cyS2RMV0RkMVVYZ2I1?= =?utf-8?B?UmNBTjBLNEt0RU5zMEloWWtMaTI3ZkRlR1lCK2VYZkVrc2g5OU9GZTBFak9u?= =?utf-8?B?ZnpaRE1NQU5ndEU4QWNUMU1wd20wM0ttdlJWc2MwelpMQzRhY2N1TStaU0xQ?= =?utf-8?B?NDhoQjdEK2FvMXFyaUMwc3VVa0pDWUJpY0NMVjZQMVlEckNMcUUwc0d1Vms4?= =?utf-8?B?RWN3ck8rWVF5dkVTVHhzWDNHZ2c0QUxUVndkMmFndjEydWJPNXpmK3pHdmRX?= =?utf-8?B?OGI1Z2kzeVA3YnF6Y3pKYjF5OTNhbVpJRmRhZXFZVUkycHIyZjRqMmdLK1NS?= =?utf-8?B?cGZzUDJvKzAzYTkvWjFURnFCcHl2dWo2cmluSFZiSnZZeTB1Q0k5WnN1R21t?= =?utf-8?B?SU5QN0JuZ0tGaVg1Y1liejQwTFBFTkdMc0ROMEgvMU9IYm5zMFZ5ZmMyeU5T?= =?utf-8?B?U25JU1F3b0RxVWg5WHlRdlc2dUh6SHo2U2xlVmNGcG55T09LQmJrM3JDMStU?= =?utf-8?B?RnJ2RUdIZEZ2VkplbzZBcmcrZVRORlFPbzNiSDA1ZHY3ZDlxYzdmQzN1cG1G?= =?utf-8?B?VmlQUDFiWE5kdzR5Mi8zcmRCVi92VHJHY0JJbHFvRFIzbEt0RXorY2tZVloz?= =?utf-8?B?ZVNlNmdNVXVHVmFsbDQ3R0hqUlVWMHp0NzI2WTVwc3UxS1IyejNsTUtQL0JM?= =?utf-8?B?U1lIUXpoQXg1ODdqV3ZFLzQ2WWpJbTd4MXpKT0RYQjFlNlhSVFpoU3VKOTlG?= =?utf-8?B?b1B5cjArbXlMR2tHMEFKUFM2REZPQkMwR2o4L1ZCRVJIQmNXSnU0NmJCaVlw?= =?utf-8?B?bVQzZVZ1SWgwQStEYVMxM1RPakc2OElyQmdUbUM5Q1F6UlRBQllCOWVrU1ZY?= =?utf-8?B?TFN1YmQyRUF4cElENXRqWE9iZWkzV2N2cFhtUkh3Ky82ZUkvOTRvOWFrR3NH?= =?utf-8?B?K2ZscFQ4eERJL285eVFUM29rd08wTVFMbFQzNFhCd1RrNFFaTEFqcUFEWFVJ?= =?utf-8?B?Mmt6cnFGTmNpQ3l4clRrano4TXpaUzZzWWhHM2phS2w0UFFkb0dGVEIzNHVx?= =?utf-8?B?RHNMZXhLNVczcFNJVERPQ0J3WGIzeVd0cmpVSDVJQzdTd1VhbFVHb0pVYkFn?= =?utf-8?B?b01USW5CazVRT2RYcmlIK29mdXFxMnVsRWZNVWtnRmxGeW0rdXF5eGlLQ1py?= =?utf-8?B?Tk5zRUhXR054R0dwalMva2cxTTVjVWE2eXNSK3hKelBUdnkrL3ZraUZMRGkw?= =?utf-8?Q?mUEXnmtd27V0TJtbkKd6DkA4MvwAgEZS?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:AMBPR06MB10365.eurprd06.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(376014)(366016)(1800799024);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?utf-8?B?VC9hQWt5dnlNZjRlOWM4TGVoQmg2N3ZwOFZJOTg2dTFQbnNYVnMvYmxFdFQx?= =?utf-8?B?TjhhTUVCTHFxTDJRZ3IyWnlwWG5iRG5ZV0h2UmxVZWQxd1hZdDBVY0dWVjZx?= =?utf-8?B?YXM2RktKbjgwSXFWTEFZUXJ1eUdJNUNnTkFLSnVteWtDaUpVanNLUE5yb3BW?= =?utf-8?B?U1VHZGZEQi9qZU4xdmFsYTVyUlY3cUcwdXBIa2hiQzQvcG9ZQ2QrcWFJUnR4?= =?utf-8?B?M1haYmhWNHJYTjU5cXlYSC85bk4yMmJxdlBHMktHVDZKVW45bkl1ZzYrQ3ZZ?= =?utf-8?B?R01qeHZhUVdHVzN0UWoyTXR4MWVPVGtrdEc4TEtLMEU0UFMrQ1Bpcmw2MlVP?= =?utf-8?B?UnNuVmUzM0EwdUVnL1NrNmd1QUtrVVFHQzg1SXFOYmpJazB4eXI4S3FiUzk2?= =?utf-8?B?b2RSQys5SllnWUYybWV3Mnk1REY5b3c3cDVnL01EODdQZ1Z6OVMza0ZGMkJi?= =?utf-8?B?U0Vic29SRmNwR0xoY0pldEhVZWVnbThObThGQjFvb0hOQm1QSmpHM0FIbExR?= =?utf-8?B?M200WTZnRStPcEo2d3h3aSt5U2psbjd5WituTytUck9ySjFnTDU0eEwxY0ZI?= =?utf-8?B?OFp4QXg3UXdoTmltWDQzNzh0MVVXdklXNXZ5bU9qSGwvOTg5aVhqbGdITGw5?= =?utf-8?B?Mks4Tlh5TkRnbWNyc3YrTXNNZHRsdm1ZQU5USW9iTU1SMG9VZEgyanZmUmdN?= =?utf-8?B?N1lwNTVic1lsbituVEU1VFZlcm1kOXd5U3hYb3M4bmI4aFhkWU9WSmZDUEJK?= =?utf-8?B?ZEdrcFJYdzVzZTErTE80RUllYmszVy9FVU9UcmpJdXJ4VVoyU0VpSXFpODBU?= =?utf-8?B?NmUzcVhaZlBNVU5iZmJpY0ZSdU9YSG1xb1dJV0Y4ZERHcFlaVm1WbmpWbzN3?= =?utf-8?B?VnBhLzRNS3JGKytSTU00aDdsMU1MV1ROd2hpOFQ0TDBRbXhSU3UrQzNpTlpO?= =?utf-8?B?bCswSVpxRkloV21KT05BS3RsZVZXWkdUdFJ5ZXk4cWlsR2dmb2QvRHp4ZHB4?= =?utf-8?B?azVVYksvU2VCRkRCdDVMZ0pobE1aam5sWiszMmNPSThiOHBGdDRXQ2VoZkxW?= =?utf-8?B?RmxwaHlWODZiZ0tnS2xaeGVLUmgrNnpmY2ZRcVcrVkFUZm5lUk5WNEpvZU5E?= =?utf-8?B?S1JFbkkwUFgrNHRWaHAzSzVBM1RVUUNjaU9YN3FTa08xQnl4c2N2L3FjUE93?= =?utf-8?B?MkdUeHlSRndGRzd1MmJzQ0JHSUtkTmt4YlN2MHA0T3AwVEl3S0R4WGNYQzBt?= =?utf-8?B?ZWlmMXh6UmFPbVNFY2hyNkpwWjZFcXFIVzBHR3l2OERwdm1tdVBORDFOY2pZ?= =?utf-8?B?enZPV25LcHJ1SFI3U0NsYUJwQ2djdkZvSnNjb04zTUFURWJ2VFMzR1U5RDMy?= =?utf-8?B?YVBMQk9XZTU4U0Nwa0J5VUw4K0RRaXErV3NYZnVTTERvRnQxVTltejBxMUxD?= =?utf-8?B?bWJ5T3lvdVRYbE40SDE2b2tmMFhsRVpXbWNTdzFtWm56SHA2QXRObnh5VHI0?= =?utf-8?B?UXVZTHl2Y1NHQVEwU3k0K0tTa3JxdVZBTitZaWxmZzBLN2M3clJKOVYwbmFm?= =?utf-8?B?ckVTUzg4d2c3UmxCaFZiOUZobjVoVitOWEV3TEluNjk4Y3gxSHNGbTdOb0gy?= =?utf-8?B?dkN6djFyek9qZGZXTzdaeERyYmgyYUtPTTd2cjhxWFVMZUQ3QWxRY1RPTzh0?= =?utf-8?B?eHZEaXZyOVEvWGpVS0wwRW5MaEFOOEh3OWNqUGNQOE1xWWd4a2pvNE8zQkQ5?= =?utf-8?B?TENURUtTVDZ6ckl5ajFBRng1ZlZaUUZ1OTFPSTdQL1JaOGkwRGhOYklsem5W?= =?utf-8?B?QXprZDBoSHBIK2IzRFNqWThoRU8wd2lEbzFnTWNIa2VyOXppUnFUR3NFQkVl?= =?utf-8?B?T0ZhR2QyNkF0M1A1d2lqZGNRaG1tT1dKa0ZXci9UTDVqSElQM3ZMQjFpT1Q4?= =?utf-8?B?SEU3R1psbUo0KzRQUjVURGNBWGpnd0hQVzB0UVY0SVVLOGpoMzNRTlkzMmlm?= =?utf-8?B?SG40NUJSSGY4UmQzVlNXSDJnQlM3Y2JBQTcwc2tuZWlLaitWS2hRNUpKVkpu?= =?utf-8?B?V1VhVTMxb05ZRmRPMmtxWnhJeTJxcUs0cStCSVFYb1F5WWdYdWZWQTVIMlFt?= =?utf-8?B?VmlNTlQzUlJHQ3BNNjRlRGVWT0hROE1MUG1PeHRNODBrYTR1M2c2S0VwTTZK?= =?utf-8?B?Y1RHSERVSG1EaHF2RFZkaTlJT0VITit1cWRhUlpjN2tkL2sxVjJhU0NNOTNW?= =?utf-8?B?RGQ3eVlPQWVCVFlEVFdjZ0x1WDNQWk9OeWJDZmUvMXpYZXZTTjJUOHZYaEFk?= =?utf-8?B?OHMyU3B3cG1kYXNoanNmaFZiejYyMXlFSGt1YUhQbFVVWXBubmZaSVZJL0Zs?= =?utf-8?Q?eg+mlLHxrgd/BDRw=3D?= X-OriginatorOrg: vaisala.com X-MS-Exchange-CrossTenant-Network-Message-Id: 900e0c2d-cc1e-4d69-d616-08de4c4a98e4 X-MS-Exchange-CrossTenant-AuthSource: AMBPR06MB10365.eurprd06.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 05 Jan 2026 11:07:21.0739 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 6d7393e0-41f5-4c2e-9b12-4c2be5da5c57 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: vUisjcBrUDyDfl1YB2hIzBRwWzonoOPTdqP19ye+Q/20UOsXDCsEauL2q3NF9qAZggbpgqpW03d/veMp/MOTxQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: AS5PR06MB8726 Hi, On 21/12/2025 22:00, Jonathan Cameron wrote: > On Tue, 16 Dec 2025 11:40:06 +0000 > Tomas Melin wrote: > >> Not all users can or want to use the device with an iio-backend. >> For these users, let the driver work in standalone mode, not coupled >> to the backend or the services it provides. >> >> Signed-off-by: Tomas Melin > Hi Tomas, > >> static int ad9467_probe(struct spi_device *spi) >> @@ -1352,21 +1361,25 @@ static int ad9467_probe(struct spi_device *spi) >> indio_dev->channels = st->info->channels; >> indio_dev->num_channels = st->info->num_channels; >> >> + /* Using a backend is optional */ > > I'll largely defer to Nuno on the backend aspects but I would like a > lot more than a statement that it is optional in this comment. > At least something about where the data goes and what a real system > that didn't provide a backend would look like etc. Having the backend as optional is about flexibility to incorporate these devices as fits best with the system. The current backend approach is pretty much dictated with how the ADI default backend is implemented. These devices are fully configurable via SPI interface so the backend doesn't necessarily need to be anything fancy or even configurable. So there is atleast two use cases that promote the optional iio-backend approach - simple backend that is not configurable, no need for a dedicated driver. The backend (FPGA) sits and waits for data and handles it when it arrives - custom backend not compatible with the adi backend features. For example different approach to calibration, or other model for data channels etc. Not having it optional would mean more or less vendor lock with analog devices backend which probably was not the idea when adding the iio-backend feature in the first place. Regarding the comment, perhaps something like /** * Backend provided features are optional. If a compatible backend is * not present all features might not be available. If the system * otherwise provides a path for the data, the device will still be * fully functional. **/ > > I can think of some setups where I'd be fine with this change and others > where I'd push back harder. Given the explanations above, I'd be happy to have some more feedback on this. Thanks, Tomas > > Jonathan >