Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752026AbaDWWpR (ORCPT ); Wed, 23 Apr 2014 18:45:17 -0400 Received: from mail-pd0-f175.google.com ([209.85.192.175]:35011 "EHLO mail-pd0-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751600AbaDWWpM (ORCPT ); Wed, 23 Apr 2014 18:45:12 -0400 Message-ID: <53584277.7000405@gmail.com> Date: Wed, 23 Apr 2014 15:45:11 -0700 From: Frank Rowand Reply-To: frowand.list@gmail.com User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130801 Thunderbird/17.0.8 MIME-Version: 1.0 To: Greg Kroah-Hartman CC: Grant Likely , Rob Herring , Linux Kernel list , "devicetree@vger.kernel.org" Subject: Re: [PATCH] sysfs, device-tree: aid for debugging device tree boot problems References: <53571685.5060403@gmail.com> <20140423032044.GA26233@kroah.com> In-Reply-To: <20140423032044.GA26233@kroah.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/22/2014 8:20 PM, Greg Kroah-Hartman wrote: > On Tue, Apr 22, 2014 at 06:25:25PM -0700, Frank Rowand wrote: >> Create some infrastructure to aid trouble shooting device tree related >> boot issues. >> >> Add a %driver_name file to each device tree node sysfs directory which has had >> a driver bound to it. This allows detecting device tree nodes which failed >> to be bound to any driver. > > Why is this needed, shouldn't there already be a "driver" symlink in > sysfs for these devices when a driver binds to them? The rest of the > driver model works that way, why is of devices any different? Yes, the devices do have a "driver" symlink in sysfs. The problem I had was that I could not deterministically determine the device name in /sysfs that was associated with a device tree node that the device was created for. And I couldn't find a link from the device tree entries to the device tree node. Grant's reply to your email provided the solution to my problem; the device uevents file contains the full device tree path of the associated device tree node. Grant's reply removes the need for my patch. > >> Examples of using the %driver_name file (note that /proc/device-tree is a >> link to the base of the device tree sysfs tree): >> >> >> 1) To find list of device tree nodes with no driver: >> >> # A few false positives may be reported. For example, >> # node_full_path of "." is the board. >> # >> # output is: node_full_path compatible_string >> # >> cd /proc/device-tree >> for k in `find . -type d`; do >> if [[ -f ${k}/compatible && ! -f ${k}/%driver_name ]] ; then >> if [[ "`cat ${k}/compatible`" != "simple-bus" ]] ; then >> echo `echo ${k} | sed -e 's|./||'` `cat ${k}/compatible` >> fi >> fi >> done | sort >> >> >> 2) To find list of device tree nodes with a bound driver: >> >> # output is: node_full_path driver_name >> # >> cd /proc/device-tree >> for k in `find . -name %driver_name` ; do >> echo `echo ${k} | sed -e 's|./||' -e 's|/%driver_name$||'` `cat ${k}` >> done | sort >> >> >> 3) To find list of device tree nodes with a bound driver: >> >> # output is: driver_name node_full_path >> # >> cd /proc/device-tree >> for k in `find . -name %driver_name` ; do >> echo `cat ${k}` `echo ${k} | sed -e 's|./||' -e 's|/%driver_name$||'` >> done | sort > > If we take this patch, these examples should be somewhere in the > documentation to make it easy for others. That is a good idea. I'll package up the equivalent shell code from Grant's email. Any suggestions on location? scripts/debug/devicetree/ scripts/devicetree/debug/ Documentation/devicetree/scripts/ If there is no good location in the kernel tree, then I will put them either on the devicetree wiki, or the devicetree section of the elinux wiki. > >> Signed-off-by: Frank Rowand > > Minor nit, your From: line doesn't match this signed-off-by: so > something has to change (or add a new From: line, like SubmittingPatches > decribes how to do.) Oops, thanks for pointing that out. > > thanks, > > greg k-h -Frank -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/