From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751070AbdALS1x (ORCPT ); Thu, 12 Jan 2017 13:27:53 -0500 Received: from imap0.codethink.co.uk ([185.43.218.159]:51005 "EHLO imap0.codethink.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750908AbdALS0T (ORCPT ); Thu, 12 Jan 2017 13:26:19 -0500 Message-ID: <1484245571.10206.28.camel@codethink.co.uk> Subject: Re: sysfs deferred_probe attribute From: Ben Hutchings To: Greg Kroah-Hartman Cc: Rob Herring , "Rafael J. Wysocki" , Mark Brown , Tomeu Vizoso , Geert Uytterhoeven , "linux-kernel@vger.kernel.org" , Thierry Reding Date: Thu, 12 Jan 2017 18:26:11 +0000 In-Reply-To: <20170112174142.GA23954@kroah.com> References: <20170112174142.GA23954@kroah.com> Organization: Codethink Ltd. Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.9-1+b1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2017-01-12 at 18:41 +0100, Greg Kroah-Hartman wrote: > On Thu, Jan 12, 2017 at 11:27:01AM -0600, Rob Herring wrote: > > I just noticed that we have a new device attribute 'deferred_probe' > > added in 4.10 with this commit: > > > > commit 6751667a29d6fd64afb9ce30567ad616b68ed789 > > Author: Ben Hutchings > > Date: Tue Aug 16 14:34:18 2016 +0100 > > > > driver core: Add deferred_probe attribute to devices in sysfs > > > > It is sometimes useful to know that a device is on the deferred probe > > list rather than, say, not having a driver available. Expose this > > information to user-space. > > > > Signed-off-by: Ben Hutchings > > Signed-off-by: Greg Kroah-Hartman > > > > > > It seems like a bad idea to add an ABI for an internal kernel feature. > > When/if we replace deferred probe with something better based on > > functional dependencies are we going to keep this attr around? Or > > remove it and assume no userspace uses it? It should be removed then (and replaced with some kind of representation of dependencies). > > Perhaps it should be hidden > > behind CONFIG_DEBUG or just make a debugfs file that lists the > > deferred list. Then you wouldn't have to hunt for what got deferred. > > Ah, debugfs would be nice, I'd much prefer that. I don't know how Ben > is using this, but I think that would make more sense to me. I'm not using it any programmatic way, and don't intend to. debugfs would be OK, but attaching it to devices was easy to do and seemed to make sense. Ben. -- Ben Hutchings Software Developer, Codethink Ltd.