From: Mitch Bradley <wmb-D5eQfiDGL7eakBO8gow8eQ@public.gmane.org>
To: Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
Cc: Kevin Hilman <khilman-l0cyMroinI0@public.gmane.org>,
Matt Porter <mporter-l0cyMroinI0@public.gmane.org>,
Koen Kooi
<koen-QLwJDigV5abLmq1fohREcCpxlwaOVQ5f@public.gmane.org>,
Pantelis Antoniou
<panto-wVdstyuyKrO8r51toPun2/C9HSW9iNxf@public.gmane.org>,
linux-kernel
<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
Felipe Balbi <balbi-l0cyMroinI0@public.gmane.org>,
Deepak Saxena <dsaxena-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>,
Russ Dill <Russ.Dill-l0cyMroinI0@public.gmane.org>,
Scott Wood <scottwood-KZfg59tc24xl57MIdRCFDg@public.gmane.org>,
linux-omap-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
devicetree-discuss-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org
Subject: Re: [RFC] Device Tree Overlays Proposal (Was Re: capebus moving omap_devices to mach-omap2)
Date: Tue, 13 Nov 2012 08:10:11 -1000 [thread overview]
Message-ID: <50A28D03.7050002@firmworks.com> (raw)
In-Reply-To: <50A27BF1.4030502-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
It seems to me that this capebus discussion is missing an important
point. The name capebus suggests that it is a bus, so there should be a
parent node to represent that bus. It should have a driver whose API
implements all of the system-interface functions a cape needs.
If you look at the way that interrupt specifiers work, the default case
is that a child device implicitly delegates the mapping to its parent.
The use of phandles to break out of the tree structure was intended for
use within the "hardwired motherboard domain", not for plug-in devices.
The "new" phandle-based GPIO and clock mechanisms don't have that
parent-delegation feature, but they should, because hierarchical
hardware is a good thing when it exists. One fix would be to designate
a reserved phandle value - for example 0 or -1 - to mean "my parent". t
The parent node would contain some translator to resolve the actual
target node, similarly to interrupts and addresses.
If done correctly, capebus "overlays" would then just be proper child
nodes of the capebus bus node and there would no need to refer to
"global" information like non-parent phandles.
If something about the design of capebus makes that impossible, I
respectfully suggest that its design should be reviewed, taking into
account the many years of industry experience about modularity.
Mitch
next prev parent reply other threads:[~2012-11-13 18:10 UTC|newest]
Thread overview: 99+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-05 20:40 [RFC] Device Tree Overlays Proposal (Was Re: capebus moving omap_devices to mach-omap2) Grant Likely
2012-11-06 10:30 ` Pantelis Antoniou
2012-11-06 11:14 ` Grant Likely
2012-11-06 18:35 ` Tony Lindgren
2012-11-06 19:29 ` Russ Dill
[not found] ` <CA+Bv8XZOt7h3dtDsk1SaR71J3tYFOTsPJSjZLSP3RVuLdYdFDg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-11-06 19:41 ` Pantelis Antoniou
2012-11-06 22:17 ` Stephen Warren
2012-11-06 19:34 ` Pantelis Antoniou
2012-11-06 20:45 ` Grant Likely
2012-11-06 20:50 ` Grant Likely
2012-11-07 8:06 ` Pantelis Antoniou
2012-11-07 15:33 ` Alan Tull
2012-11-09 17:03 ` Grant Likely
2012-11-07 8:13 ` Pantelis Antoniou
[not found] ` <5ED17D42-07B8-4D4F-B54F-82B4CC60584C-wVdstyuyKrO8r51toPun2/C9HSW9iNxf@public.gmane.org>
2012-11-07 10:19 ` Benoit Cousson
2012-11-07 11:02 ` Pantelis Antoniou
[not found] ` <A6697FB9-3614-4027-A71B-59C7556005BF-wVdstyuyKrO8r51toPun2/C9HSW9iNxf@public.gmane.org>
2012-11-07 11:12 ` Benoit Cousson
2012-11-07 11:23 ` Pantelis Antoniou
2012-11-09 20:33 ` Grant Likely
2012-11-12 11:34 ` Pantelis Antoniou
2012-11-12 13:01 ` Grant Likely
2012-11-07 17:25 ` Stephen Warren
[not found] ` <509A9984.3000709-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2012-11-07 22:10 ` Pantelis Antoniou
2012-11-08 10:36 ` Cousson, Benoit
2012-11-09 5:32 ` Joel A Fernandes
2012-11-09 14:29 ` David Gibson
2012-11-10 3:15 ` Joel A Fernandes
2012-11-09 21:22 ` Grant Likely
[not found] ` <CACxGe6vL9gbAKyDWcZWWAQ4WO=nTgdAioXS-h2e1jtJK9pmZUg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-11-12 11:47 ` Pantelis Antoniou
2012-11-13 3:59 ` Joel A Fernandes
2012-11-09 22:59 ` Stephen Warren
[not found] ` <-4237940489086529028@unknownmsgid>
[not found] ` <559B8433-67C3-4A1A-A5D6-859907655176@antoniou-consulting.com>
[not found] ` <559B8433-67C3-4A1A-A5D6-859907655176-wVdstyuyKrO8r51toPun2/C9HSW9iNxf@public.gmane.org>
2012-11-10 3:36 ` Joel A Fernandes
2012-11-12 12:48 ` Pantelis Antoniou
2012-11-13 2:28 ` David Gibson
2012-11-09 2:26 ` David Gibson
2012-11-09 15:40 ` Pantelis Antoniou
[not found] ` <A97699E9-6C57-4A56-BC45-86A57CF2496F-wVdstyuyKrO8r51toPun2/C9HSW9iNxf@public.gmane.org>
2012-11-13 0:03 ` David Gibson
2012-11-09 21:08 ` Grant Likely
[not found] ` <CACxGe6v7q2=Dxn6BE_V-w9CEKxAsZ6zQd5Uqm4TeYGYCCu76cg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-11-13 0:05 ` David Gibson
2012-11-09 21:42 ` Grant Likely
[not found] ` <CACxGe6vQ50aS0Fe7QvTHKfV=EDpsZoLC7SOxXLGc0pkMvyk5DQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-11-13 1:05 ` David Gibson
2012-11-13 5:22 ` Stephen Warren
[not found] ` <50A1D8FF.7060104-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2012-11-13 6:54 ` David Gibson
2012-11-09 22:57 ` Stephen Warren
2012-11-09 23:27 ` Grant Likely
2012-11-12 12:05 ` Pantelis Antoniou
[not found] ` <20121109022624.GI23553-W9XWwYn+TF0XU02nzanrWNbf9cGiqdzd@public.gmane.org>
2012-11-09 23:14 ` Stephen Warren
2012-11-09 23:06 ` Stephen Warren
2012-11-09 23:32 ` Grant Likely
[not found] ` <CACxGe6vu8ek7-K-yDDMXyg9x-oKiFt_cSz+Pz-yZf5U5vwe=0g-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-11-05 21:40 ` Tabi Timur-B04825
2012-11-05 23:22 ` Tony Lindgren
[not found] ` <20121105232218.GA8284-4v6yS6AI5VpBDgjK7y7TUQ@public.gmane.org>
2012-11-09 12:06 ` Grant Likely
2012-11-06 0:07 ` Grant Likely
2012-11-06 10:31 ` Pantelis Antoniou
2012-11-07 22:35 ` Ryan Mallon
2012-11-08 13:28 ` Koen Kooi
2012-11-08 14:09 ` Timur Tabi
2012-11-08 17:00 ` Mitch Bradley
2012-11-06 22:37 ` Stephen Warren
[not found] ` <50999145.2070306-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2012-11-07 0:54 ` Mitch Bradley
2012-11-09 17:02 ` Grant Likely
2012-11-12 11:29 ` Pantelis Antoniou
2012-11-07 8:47 ` Pantelis Antoniou
2012-11-07 17:18 ` Stephen Warren
[not found] ` <509A97D0.5010006-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2012-11-07 22:08 ` Pantelis Antoniou
2012-11-09 16:28 ` Grant Likely
2012-11-09 23:23 ` Stephen Warren
2012-11-09 23:40 ` Grant Likely
2012-11-12 10:53 ` Koen Kooi
[not found] ` <509D9089.7020407-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2012-11-12 12:10 ` Pantelis Antoniou
2012-11-12 16:52 ` Stephen Warren
2012-11-13 7:25 ` David Gibson
[not found] ` <20121113072517.GE25915-W9XWwYn+TF0XU02nzanrWNbf9cGiqdzd@public.gmane.org>
2012-11-13 8:09 ` Pantelis Antoniou
2012-11-13 12:24 ` Grant Likely
[not found] ` <CACxGe6vQxmAk_joUYbaXw4r8J3_RbQt22zFg84ANvcw+ycCMHg-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2012-11-13 13:38 ` Pantelis Antoniou
2012-11-15 4:57 ` David Gibson
2012-11-13 17:10 ` Stephen Warren
[not found] ` <BD20AE03-C138-4BC6-AE02-F162AF6840B2-wVdstyuyKrO8r51toPun2/C9HSW9iNxf@public.gmane.org>
2012-11-13 23:30 ` David Gibson
2012-11-14 0:00 ` Pantelis Antoniou
2012-11-13 16:57 ` Stephen Warren
[not found] ` <50A27BF1.4030502-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>
2012-11-13 18:10 ` Mitch Bradley [this message]
[not found] ` <50A28D03.7050002-D5eQfiDGL7eakBO8gow8eQ@public.gmane.org>
2012-11-13 18:29 ` Stephen Warren
2012-11-13 19:09 ` Mitch Bradley
2012-11-13 19:11 ` Pantelis Antoniou
2012-11-17 22:27 ` Jean-Christophe PLAGNIOL-VILLARD
2012-11-20 17:09 ` Grant Likely
2012-11-11 20:47 ` Rob Landley
2012-11-12 12:50 ` Pantelis Antoniou
[not found] ` <ABAD0875-A618-405D-954F-CD76F09DDF04-wVdstyuyKrO8r51toPun2/C9HSW9iNxf@public.gmane.org>
2012-11-12 16:54 ` Stephen Warren
2012-11-12 11:23 ` Pantelis Antoniou
2012-11-12 16:49 ` Stephen Warren
2012-11-12 17:00 ` Pantelis Antoniou
2012-11-12 17:10 ` Stephen Warren
2012-11-12 17:19 ` Pantelis Antoniou
2012-11-12 17:29 ` Stephen Warren
2012-11-12 17:38 ` Pantelis Antoniou
2012-11-12 20:16 ` Russ Dill
2012-11-12 16:45 ` Stephen Warren
2012-11-12 11:03 ` Koen Kooi
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