From mboxrd@z Thu Jan 1 00:00:00 1970 From: holler@ahsoftware.de (Alexander Holler) Date: Wed, 14 May 2014 20:16:53 +0200 Subject: [RFC PATCH 0/9] dt: dependencies (for deterministic driver initialization order based on the DT) In-Reply-To: <5373ADB6.1070702@ahsoftware.de> References: <1399913280-6915-1-git-send-email-holler@ahsoftware.de> <20140514141914.446F7C4153D@trevor.secretlab.ca> <53738580.7000902@ahsoftware.de> <53739871.9070407@ahsoftware.de> <5373ABD2.9010508@ahsoftware.de> <5373ADB6.1070702@ahsoftware.de> Message-ID: <5373B315.3020909@ahsoftware.de> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Am 14.05.2014 19:53, schrieb Alexander Holler: > Am 14.05.2014 19:45, schrieb Alexander Holler: > >> One of the biggest problem of the deferred probe stuff is the problem >> how to identify real problems if everything ends up with a deferred >> probe when an error occurs? That means if you display an error whenever >> something is deferred, the log becomes almost unreadable. If you don't >> display an error, you never will see an error. And how do you display >> the real error when deferred probes finally do fail? The deferred probe >> stuff doesn't has any information about the underlying error, so it >> can't display it. > > And that is a real problem. I've recently tried to identify why a driver > failed and it was a nightmare because nothing offered any message (debug > or not) when a probe was deferred. So I had to insert tons of printks to > walk upwards to find the finally place where the probe failed. > Everything afterwards just has forwarded the -EPROBE_DEFER without > printing any message. To add some numbers, I had to insert around 20-30 printks in around 10 or more files to find the underlying problem. Having to do such whenever an error happens because everything assumes the error will disappear in a later try, which doesn't happen for real errors, is just a nightmare. Regards, Alexander Holler From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alexander Holler Subject: Re: [RFC PATCH 0/9] dt: dependencies (for deterministic driver initialization order based on the DT) Date: Wed, 14 May 2014 20:16:53 +0200 Message-ID: <5373B315.3020909@ahsoftware.de> References: <1399913280-6915-1-git-send-email-holler@ahsoftware.de> <20140514141914.446F7C4153D@trevor.secretlab.ca> <53738580.7000902@ahsoftware.de> <53739871.9070407@ahsoftware.de> <5373ABD2.9010508@ahsoftware.de> <5373ADB6.1070702@ahsoftware.de> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5373ADB6.1070702-SXC+2es9fhnfWeYVQQPykw@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Rob Herring Cc: Grant Likely , Linux Kernel Mailing List , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Jon Loeliger , Russell King , Greg Kroah-Hartman , Rob Herring , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" List-Id: devicetree@vger.kernel.org Am 14.05.2014 19:53, schrieb Alexander Holler: > Am 14.05.2014 19:45, schrieb Alexander Holler: > >> One of the biggest problem of the deferred probe stuff is the problem >> how to identify real problems if everything ends up with a deferred >> probe when an error occurs? That means if you display an error whenever >> something is deferred, the log becomes almost unreadable. If you don't >> display an error, you never will see an error. And how do you display >> the real error when deferred probes finally do fail? The deferred probe >> stuff doesn't has any information about the underlying error, so it >> can't display it. > > And that is a real problem. I've recently tried to identify why a driver > failed and it was a nightmare because nothing offered any message (debug > or not) when a probe was deferred. So I had to insert tons of printks to > walk upwards to find the finally place where the probe failed. > Everything afterwards just has forwarded the -EPROBE_DEFER without > printing any message. To add some numbers, I had to insert around 20-30 printks in around 10 or more files to find the underlying problem. Having to do such whenever an error happens because everything assumes the error will disappear in a later try, which doesn't happen for real errors, is just a nightmare. Regards, Alexander Holler -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751517AbaENSRl (ORCPT ); Wed, 14 May 2014 14:17:41 -0400 Received: from h1446028.stratoserver.net ([85.214.92.142]:47952 "EHLO mail.ahsoftware.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751216AbaENSRj (ORCPT ); Wed, 14 May 2014 14:17:39 -0400 Message-ID: <5373B315.3020909@ahsoftware.de> Date: Wed, 14 May 2014 20:16:53 +0200 From: Alexander Holler User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Rob Herring CC: Grant Likely , Linux Kernel Mailing List , "devicetree@vger.kernel.org" , Jon Loeliger , Russell King , Greg Kroah-Hartman , Rob Herring , "linux-arm-kernel@lists.infradead.org" Subject: Re: [RFC PATCH 0/9] dt: dependencies (for deterministic driver initialization order based on the DT) References: <1399913280-6915-1-git-send-email-holler@ahsoftware.de> <20140514141914.446F7C4153D@trevor.secretlab.ca> <53738580.7000902@ahsoftware.de> <53739871.9070407@ahsoftware.de> <5373ABD2.9010508@ahsoftware.de> <5373ADB6.1070702@ahsoftware.de> In-Reply-To: <5373ADB6.1070702@ahsoftware.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Am 14.05.2014 19:53, schrieb Alexander Holler: > Am 14.05.2014 19:45, schrieb Alexander Holler: > >> One of the biggest problem of the deferred probe stuff is the problem >> how to identify real problems if everything ends up with a deferred >> probe when an error occurs? That means if you display an error whenever >> something is deferred, the log becomes almost unreadable. If you don't >> display an error, you never will see an error. And how do you display >> the real error when deferred probes finally do fail? The deferred probe >> stuff doesn't has any information about the underlying error, so it >> can't display it. > > And that is a real problem. I've recently tried to identify why a driver > failed and it was a nightmare because nothing offered any message (debug > or not) when a probe was deferred. So I had to insert tons of printks to > walk upwards to find the finally place where the probe failed. > Everything afterwards just has forwarded the -EPROBE_DEFER without > printing any message. To add some numbers, I had to insert around 20-30 printks in around 10 or more files to find the underlying problem. Having to do such whenever an error happens because everything assumes the error will disappear in a later try, which doesn't happen for real errors, is just a nightmare. Regards, Alexander Holler