From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mgamail.intel.com (mgamail.intel.com [198.175.65.16]) (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 041491E9B22; Thu, 27 Nov 2025 09:05:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.175.65.16 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764234317; cv=none; b=WKDpdy47qUN+5862siCjcfjiXqt6Lqca2eVwlzNx25WXPMzUfh8Ii1eQ4txciwfqyOC0Cf4FCd3MtOq5sNcPON+cfgnEBelrd6X7XA34iomi6roYr0Lj4Iu2Bt8c9hltFABd3+mImE9CkJ7vHuuT0bn01PxfB1H1t/VA1SDm+Nc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1764234317; c=relaxed/simple; bh=uzezHOgdfjxeuuqh9PuAC2SBUnz1PWD2xz4Zeeitw4I=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=GahQiGFoxjoUcl5zYHbBHIULnoU0WWzw8rQRWuE9uwxbPurdt9i8liLQzKpOk4Rlw9ezul05KPKmqtX1uEGb65vrPZS1paFbiP82A+tCTZoOu4Jn53FuNxhlvXiRLX270eUV7VbE3p1cl0sJkNmHvn+y0As13AB2Q4Jq/TzXi1U= 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=cFt1Jt85; arc=none smtp.client-ip=198.175.65.16 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="cFt1Jt85" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1764234316; x=1795770316; h=date:from:to:cc:subject:message-id:references: mime-version:content-transfer-encoding:in-reply-to; bh=uzezHOgdfjxeuuqh9PuAC2SBUnz1PWD2xz4Zeeitw4I=; b=cFt1Jt85HcxMIZJo8a7pLNlH8QHskcDqDxa14vUOrZ+1zB3nfRXBmLq8 ue0UylM7G9HCfXLuPF5ujz6sPptow2Wbo7419zZad1hWIoBnxWtaSkvDE ZnU0oJCIL6LM7SvYpQcdWePpx9gDt33xSYmqVcWmt67pzVQk1BehTL83/ x43zxLYFRETHPbmxVis9CmXekPCuicNrQv1gI0xUAddyK+iJQQqIZDNZv P2laN7+1JoZjEwMtwU3eAteegG4bxvyah8RcFHCrWVDTHj3Vsy2LTpMOY Koa5P8EvMjXeiLH/R0WUw8jr5byMAO+zd6kmYctVwk7+5Ce8lm3r0gB7P g==; X-CSE-ConnectionGUID: JxO/zr6sTyeOlAtahO/xPg== X-CSE-MsgGUID: w+vXYidgQbWMGGTDsnfSDA== X-IronPort-AV: E=McAfee;i="6800,10657,11625"; a="66439348" X-IronPort-AV: E=Sophos;i="6.20,230,1758610800"; d="scan'208";a="66439348" Received: from fmviesa006.fm.intel.com ([10.60.135.146]) by orvoesa108.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Nov 2025 01:05:12 -0800 X-CSE-ConnectionGUID: 5j94vtkzQD667j0HMuR3qg== X-CSE-MsgGUID: gMiMBeKxQW+WzGiRQgGI2Q== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.20,230,1758610800"; d="scan'208";a="193081676" Received: from abityuts-desk.ger.corp.intel.com (HELO localhost) ([10.245.245.225]) by fmviesa006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 27 Nov 2025 01:05:08 -0800 Date: Thu, 27 Nov 2025 11:05:06 +0200 From: Andy Shevchenko To: wenhua lin Cc: Wenhua Lin , Greg Kroah-Hartman , Jiri Slaby , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Orson Zhai , Baolin Wang , Chunyan Zhang , Cixi Geng , linux-kernel@vger.kernel.org, linux-serial@vger.kernel.org, Xiongpeng Wu , Zhaochen Su , Zhirong Qiu Subject: Re: [PATCH] serial: sprd: Return -EPROBE_DEFER when uart clock is not ready Message-ID: References: <20251022030840.956589-1-Wenhua.Lin@unisoc.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Organization: Intel Finland Oy - BIC 0357606-4 - c/o Alberga Business Park, 6 krs, Bertel Jungin Aukio 5, 02600 Espoo On Thu, Nov 27, 2025 at 04:44:08PM +0800, wenhua lin wrote: > On Wed, Nov 26, 2025 at 8:57 PM Andy Shevchenko > wrote: > > On Wed, Oct 22, 2025 at 11:08:40AM +0800, Wenhua Lin wrote: ... > > > clk_uart = devm_clk_get(uport->dev, "uart"); > > > if (IS_ERR(clk_uart)) { > > > + if (PTR_ERR(clk_uart) == -EPROBE_DEFER) > > > + return -EPROBE_DEFER; > > > + > > > dev_warn(uport->dev, "uart%d can't get uart clock\n", > > > uport->line); > > > clk_uart = NULL; > > > > AFAICS this still ignores other issues, what should be done here is to > > replace devm_clk_get() by devm_clk_get_optional() and drop this NULL > > assignment. > The main reason for this change is that the UART driver is > built-in, while the CLK driver is loaded as a module (ko). > There may be a situation where the UART driver is loaded first. If > an EPROBE_DEFER error occurs, the driver will return directly > and continue waiting for the CLK driver to complete loading. > If this interface is changed to devm_clk_get_optional, in scenarios > where dependent components are not yet loaded, > it will no longer return EPROBE_DEFER but instead return null. This > behavior may not align with the desired outcome. No, the _optional does exactly what your code does with the better approach that may return other errors _in addition to_ the current state of affairs. So, please switch to _optional variant and drop all that unneeded dances. clk_uart = devm_clk_get_optional(uport->dev, "uart"); if (IS_ERR(clk_uart)) { return dev_err_probe(uport->dev, PTR_ERR(clk_uart), "uart%d can't get uart clock\n", uport->line); this will return an error when clock is present, but can't be retrieved. When there is no clock provided at all, it will return NULL. > > > clk_parent = devm_clk_get(uport->dev, "source"); > > > if (IS_ERR(clk_parent)) { > > > + if (PTR_ERR(clk_parent) == -EPROBE_DEFER) > > > + return -EPROBE_DEFER; > > > + > > > dev_warn(uport->dev, "uart%d can't get source clock\n", > > > uport->line); > > > clk_parent = NULL; Ditto. -- With Best Regards, Andy Shevchenko