From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.16]) (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 637DA3D6CCF; Thu, 15 Oct 2026 18:41:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=192.198.163.16 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792089709; cv=none; b=Od1Bx2tYxtVf6tR1QXOKGlT6ZExrOUVUZdCO/IQHKUv/zQco+vkkd9WqsDfIlNtf9VgVZhLdeZFPoXNw2By8EJkwu9KnZJlnY9MQorddDtLW9hrXlqwz5awlDZ98ZOub+0URkOfx0KPqd0StDlc2C1XUsih3nPMxlnGdPl/kBeg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792089709; c=relaxed/simple; bh=m8N3+5cR3Lgd93wxfdvA9OwDbvRJdyGpsxTIuxZx3FA=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Bvq6vK/ZNqehHMWkrCenkiZ60bT9q7J3FE2mPnmXATruhihQgKbfdW1KWD7vi8M8W64fhnTvcXIwo1EUXDql7sG20c3PoFXT/OkASee0JP3p6CWkdLgziMp5fvwF9Lk46E9XBai6ECfiaAEGkMB96GZylqw8UK3cSOdLku5OAD0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com; spf=pass smtp.mailfrom=intel.com; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b=IDHk8GVC; arc=none smtp.client-ip=192.198.163.16 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=intel.com header.i=@intel.com header.b="IDHk8GVC" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1792089708; x=1823625708; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=m8N3+5cR3Lgd93wxfdvA9OwDbvRJdyGpsxTIuxZx3FA=; b=IDHk8GVCUnevp92D2+372v9c7xjWD3yGjDtl1SJc579XLN6riLq0e4Db 9YK1BE/HhsatgvxjIk1DJQja/MrIQu4nzOJniA5QlMPHze0wHq3YA7/li zqulCB48NCiPk0gZK1FVvY/vf8XIsvkCP0+67dmjwqv8d9ykXiPMdqRqx Hl2nuBQ3pV2iT806i+r5E65+qeQlbL/Dyu7aoo3FsKpRKt7ZbB3VMOy3I QfFe79nOMLP0lJVLGLJVsR9G2lJHiYREBhIukdjJnE2lQBDM0JjrJUWA0 LuBKuvOk23Pm4/+EJ/ZN3DIXNzhP5a3sULsYDb346/ivuQuUkeN0ApW5t w==; X-CSE-ConnectionGUID: gT6IkueXTwWjWbr1v+1XJw== X-CSE-MsgGUID: lDIa9KVRRxu8+/hAwX68ow== X-IronPort-AV: E=McAfee;i="6800,10657,11936"; a="881307" X-IronPort-AV: E=Sophos;i="6.27,160,1787036400"; d="scan'208";a="881307" Received: from fmviesa007.fm.intel.com ([10.60.135.147]) by fmvoesa110.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Oct 2026 11:41:46 -0700 X-CSE-ConnectionGUID: Q9r+r6TDRm+2gcMiJ7B0DQ== X-CSE-MsgGUID: L8ICcmHiSDufiUiNDQjCBA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,160,1787036400"; d="scan'208";a="2081424" Received: from abityuts-desk1.ger.corp.intel.com (HELO localhost) ([10.245.244.117]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 15 Oct 2026 11:41:43 -0700 Date: Thu, 15 Oct 2026 21:41:40 +0300 From: Andy Shevchenko To: rodrigo.alencar@analog.com Cc: linux-iio@vger.kernel.org, linux-kernel@vger.kernel.org, linux@analog.com, devicetree@vger.kernel.org, linux-pwm@vger.kernel.org, linux-doc@vger.kernel.org, Jonathan Cameron , Olivier Moysan , Jonathan Cameron , David Lechner , Andy Shevchenko , Michael Hennerich , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= , Jonathan Corbet , Shuah Khan , Randy Dunlap Subject: Re: [PATCH 02/10] iio: backend: add devm_iio_backend_get_optional() Message-ID: References: <20261015-ad9910-backend-support-v1-0-3c21648c8e26@analog.com> <20261015-ad9910-backend-support-v1-2-3c21648c8e26@analog.com> Precedence: bulk X-Mailing-List: linux-iio@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261015-ad9910-backend-support-v1-2-3c21648c8e26@analog.com> Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs, Bertel Jungin Aukio 5, 02600 Espoo On Thu, Oct 15, 2026 at 01:49:42PM -0300, Rodrigo Alencar via B4 Relay wrote: > Frontend devices might not need a backend driver to rely on. An IIO device > that supports backends can behave differently when they are not available > and that should be acceptable. Such parts may provide basic functionality > solely using the control interface (SPI for instance), being able to have > extended features when a backend is present. > > Add devm_iio_backend_get_optional(), which returns NULL when the backend > is not described in firmware, i.e., when the io-backends property is not > present or, for a named lookup, when the name is not listed in the > io-backend-names property. Other errors, such as probe deferral, are > still returned. > > To make that possible, a named lookup that does not match any entry of > io-backend-names now fails with -ENOENT, the same error returned when the > io-backends reference is missing. Also, the missing reference is no longer > logged as an error, leaving that to the caller. ... > struct fwnode_handle *fwnode_back __free(fwnode_handle) = > fwnode_find_reference(fwnode, "io-backends", index); > - if (IS_ERR(fwnode_back)) > + if (IS_ERR(fwnode_back)) { > + /* not described in firmware, let the caller decide what to do */ > + if (PTR_ERR(fwnode_back) == -ENOENT) > + return ERR_CAST(fwnode_back); > + > return dev_err_cast_probe(dev, fwnode_back, > "Cannot get Firmware reference\n"); > + } Simpler to do is just to add /* not described in firmware, let the caller decide what to do */ if (PTR_ERR(fwnode_back) == -ENOENT) return ERR_CAST(fwnode_back); just before IS_ERR() check. ... > ret = device_property_match_string(dev, "io-backend-names", name); > + if (ret == -EINVAL || ret == -ENODATA) > + return ERR_PTR(-ENOENT); No. Please, use device_property_present() instead. > if (ret < 0) > return ERR_PTR(ret); -- With Best Regards, Andy Shevchenko