From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f53.google.com (mail-wm1-f53.google.com [209.85.128.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2313833986E for ; Wed, 17 Dec 2025 09:25:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.53 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765963533; cv=none; b=RWpK3Vi4dpLAL893bwGkJWDWlbJ8BYGK3MQhncqX1+fcbLP5l7s9NFhPReSUjKQczjlI2Dua02JMJhvD3bk3esLXsn2CxEAgmsKfFq0zMccbG7NqCBb2PHY/jCWr5E3C5XYavUfpaBK/UTEH7eODGZcHU2077fy+ealAuc7jb8E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765963533; c=relaxed/simple; bh=mh8sWPmSpWx3ZdkV9IT1FsYBpWFgM3TDmQCsYyUuY4M=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=Ssl3aPHPxjiqjiSAEEVezg493MHmjgfpJJ6f+oX4TiS75PC7RurRFAkj7byRLJtUxLa9yrvCQ189sNSvZ7bOyhhVvyP/yGLiM+0Dvd5CY0vDPrGcT92GkXLqQeX+vTXszFhgZ4dkWztWl1+/k0w8NHqHZUlgn2dFo66vaaB0iSw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=deH2tIfd; arc=none smtp.client-ip=209.85.128.53 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="deH2tIfd" Received: by mail-wm1-f53.google.com with SMTP id 5b1f17b1804b1-477b1cc8fb4so32787225e9.1 for ; Wed, 17 Dec 2025 01:25:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1765963529; x=1766568329; darn=vger.kernel.org; h=mime-version:user-agent:content-transfer-encoding:references :in-reply-to:date:cc:to:from:subject:message-id:from:to:cc:subject :date:message-id:reply-to; bh=mh8sWPmSpWx3ZdkV9IT1FsYBpWFgM3TDmQCsYyUuY4M=; b=deH2tIfdegTEXXDfZNaDG8rU26H/FRtEwL8Jbx5YtbxLJNNb4OkCujcH61egVZAjOR HLlyMn3pog6zIhMfH9JTF8qpzPPdT4PF1SOF8wrhjVNmXdZ9g6ZJh53EeR8UBq67UFU8 35ZZ1ggrctthZ6zFkIAe+2381IxtqLwh5NfzpA4oU8FIPmjFkAC73hr+LEWAtnKwY/mG fCLXC8LU+tDW8qc9pWVsSec3DIeRiQvNhbsUxjduAbCFn4VkHrhFkFpfXRGuEPOWd++r lXTq4cxM7mkwwYV0rvOdE0g/jlnBGKTrIDGe4a8aY9Y/5fC9+Yz3/cqkpvCNB5CKlu/h vUmw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1765963529; x=1766568329; h=mime-version:user-agent:content-transfer-encoding:references :in-reply-to:date:cc:to:from:subject:message-id:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=mh8sWPmSpWx3ZdkV9IT1FsYBpWFgM3TDmQCsYyUuY4M=; b=ZYcD7Sv4XZzSLtJ2fnBKt30wyfTNaQ/1Kpmar6VNUdR5NQskhXVMrqCbGleFyUCMuC VMGZZ85Do4pcZocEFjqyufpfUuDPF+TCeWPwm4d8VyTqMCHqU3N2xUELhYtDYAz8t8PO gpYFTZi35Ok6MfGewnjx3McgWljINyfi7sBzzcF1vmgB90AJ9Li0tQaW3J2jB/2rPlEY EUOxRrLQ3Bma+sZYRZfHXjLOPeKNIXeyzEoU0rFJYIdxIXQ4L0SPXv2Ed3T4CPp+BW+W eLYO4XWx2+GtKgVuGl6Ug2EyCaugXplxGGBXHcTeAonLuWqcNNSnf65jmTGBW+N253nM hZAQ== X-Gm-Message-State: AOJu0YwCNsBgw+GlmSLkdcYUEn4kUTqFKZQcHwr9gXmfAvajWcY9sWgS /PEaBm6SRKXkar/+pfZ14KAG/egQ4r4NQO4Cl3JllglSRzJx4ls1RG2R7nOe9g== X-Gm-Gg: AY/fxX6rUDL7GLszdRp82/Blr9y0y86+aVs4OovxG8VXCjhN+UsBcaURIxVAwS4Lilz HX/Z9p7Z8FO+cHqwmlqd9CshErjPqc/8G8Hsd3IC4U43kwAxgDnyA0mzdIq4boJgqdvweDVb+63 w3dze2YaBmFyiPXeNht3U3b4IbGpfcaipxQmWZG1lkw+hATTZWn1GKFrzo8mN4HyPkYVVTQClvW 7mpeW+SOSFW81ukgLYY6wboBGXXJgHTxAsn0s0Sh557S2yxAwopN+N7GkTlYDi5TvCRG055wA8J MQ0MG23Z07+yS3e+7sjirPnSYhQqN3aGsFA0+OqT5SG5eCWKwVMNoM6PCpqjr8KFsxHaIWGNOwQ gqez4gzbE3nGkdTKPnT0rnAA7BKwq+6sEwMIfXTZLv5bHbLq1e5tvxHURY2oWB0hl72ZLgHGU7u 6dPyLO/8aE1QE= X-Google-Smtp-Source: AGHT+IG2ersucBiyzONpcJgR7W3RTu2Yc+gUs2vocQ0U+PZmiVw3HjlOZQIp3HWvl0bVa4juC08aWQ== X-Received: by 2002:a05:600c:4691:b0:471:d2f:7987 with SMTP id 5b1f17b1804b1-47a8f90ee62mr196853745e9.26.1765963529027; Wed, 17 Dec 2025 01:25:29 -0800 (PST) Received: from [10.5.0.2] ([45.94.208.162]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-47be011cc67sm1644745e9.10.2025.12.17.01.25.28 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 17 Dec 2025 01:25:28 -0800 (PST) Message-ID: Subject: Re: [PATCH 2/2] iio: adc: ad9467: make iio backend optional From: Nuno =?ISO-8859-1?Q?S=E1?= To: Tomas Melin , Michael Hennerich , Nuno Sa , Lars-Peter Clausen , Jonathan Cameron , David Lechner , Andy Shevchenko Cc: "linux-iio@vger.kernel.org" , "linux-kernel@vger.kernel.org" Date: Wed, 17 Dec 2025 09:26:10 +0000 In-Reply-To: References: <20251216-b4-ad9467-optional-backend-v1-0-83e61531ef4d@vaisala.com> <20251216-b4-ad9467-optional-backend-v1-2-83e61531ef4d@vaisala.com> <2a265681ad73bebf1ad7aeea418fb9399b8350cf.camel@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.2 Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Tue, 2025-12-16 at 15:39 +0000, Tomas Melin wrote: > Hi, >=20 > On 16/12/2025 14:56, Nuno S=C3=A1 wrote: > > On Tue, 2025-12-16 at 11:40 +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. > > >=20 > > > Signed-off-by: Tomas Melin > > > --- > >=20 > > Which users? The only usecases (for all the supported devices) we have = require > > the FPGA backend. So do you have a specific usecase for a specific devi= ce? If so, I would > > prefer an explicit boolean in the chip_info struture for the device(s) = we know this > > can happen (unless you have a usecase for all :)). >=20 > This is generically for all the devices supported by the ad9467, not > only a specific device. So it's about how this is used as part of the > design. >=20 > This is aimed at users that do not use the ADI HDL reference backend > with these devices, but instead have custom backends suited for their > own needs. Hmm, ideally I would then like to see the backend driver upstreamed... > In that case, we need to be able to skip the backend registration and > register device as a standalone iio device. >=20 > Hopefully this made the use case clearer? >=20 I mean, I don't love this and I'm not really sure I'm ok with it. These are= fairly high speed devices which often do require an FPGA IP to handle the data flo= w. Now we can ignore the backend device (which is an essential piece) being it expected or not. Or maybe we can just do something like regulators and get a dummy backend o= r just add some fixed kind of backend. Bottom line is, it still seems the backend devi= ce is a core piece in your design and we're just hacking around the driver in way that c= onceptually doesn't make sense to me. Other question that comes to mind (I guess I was not that clear)... Do you = have a real usecase with your own custom backend IP or is this just theoretical? - Nuno S=C3=A1