From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail-wm0-f67.google.com ([74.125.82.67]:36674 "EHLO mail-wm0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750737AbdGUKrC (ORCPT ); Fri, 21 Jul 2017 06:47:02 -0400 Received: by mail-wm0-f67.google.com with SMTP id 184so3930085wmo.3 for ; Fri, 21 Jul 2017 03:47:01 -0700 (PDT) Date: Fri, 21 Jul 2017 11:46:48 +0100 From: Javi Merino To: Rob Herring Cc: Mauro Carvalho Chehab , linux-media@vger.kernel.org, Sakari Ailus , Javier Martinez Canillas , Sylwester Nawrocki , Frank Rowand Subject: Re: [PATCH] Revert "[media] v4l: async: make v4l2 coexist with devicetree nodes in a dt overlay" Message-ID: <20170721104648.GA2297@ct-lt-587> References: <20170720220622.21470-1-robh@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20170720220622.21470-1-robh@kernel.org> Sender: linux-media-owner@vger.kernel.org List-ID: On Thu, Jul 20, 2017 at 05:06:22PM -0500, Rob Herring wrote: > This reverts commit d2180e0cf77dc7a7049671d5d57dfa0a228f83c1. > > The commit was flawed in that if the device_node pointers are different, > then in fact a different device is present and the device node could be > different in ways other than full_name. > > As Frank Rowand explained: > > "When an overlay (1) is removed, all uses and references to the nodes and > properties in that overlay are no longer valid. Any driver that uses any > information from the overlay _must_ stop using any data from the overlay. > Any driver that is bound to a new node in the overlay _must_ unbind. Any > driver that became bound to a pre-existing node that was modified by the > overlay (became bound after the overlay was applied) _must_ adjust itself > to account for any changes to that node when the overlay is removed. One > way to do this is to unbind when notified that the overlay is about to > be removed, then to re-bind after the overlay is completely removed. > > If an overlay (2) is subsequently applied, a node with the same > full_name as from overlay (1) may exist. There is no guarantee > that overlay (1) and overlay (2) are the same overlay, even if > that node has the same full_name in both cases." > > Also, there's not sufficient overlay support in mainline to actually > remove and re-apply an overlay to hit this condition as overlays can > only be applied from in kernel APIs. > > Cc: Mauro Carvalho Chehab > Cc: Sakari Ailus > Cc: Javi Merino > Cc: Javier Martinez Canillas > Cc: Sylwester Nawrocki > Cc: Frank Rowand > Signed-off-by: Rob Herring I've been trying to reproduce the original issues that I had for a couple of hours and I am not able to any more, so I can't object to the patch. The explanation from Frank Rowand is sound so: Acked-by: Javi Merino > --- > Mauro, please apply this for 4.13. It could be marked for stable, too, > but it's not going to apply cleanly with the fwnode changes. > > Rob > > drivers/media/v4l2-core/v4l2-async.c | 7 +------ > 1 file changed, 1 insertion(+), 6 deletions(-)