From: David Gibson <david@gibson.dropbear.id.au>
To: Grant Likely <grant.likely@secretlab.ca>
Cc: Pantelis Antoniou <panto@antoniou-consulting.com>,
Rob Herring <robherring2@gmail.com>,
Deepak Saxena <dsaxena@linaro.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Scott Wood <scottwood@freescale.com>,
Tony Lindgren <tony@atomide.com>, Kevin Hilman <khilman@ti.com>,
Matt Porter <mporter@ti.com>,
Koen Kooi <koen@dominion.thruhere.net>,
linux-kernel <linux-kernel@vger.kernel.org>,
Felipe Balbi <balbi@ti.com>, Russ Dill <Russ.Dill@ti.com>,
linux-omap@vger.kernel.org, devicetree-discuss@lists.ozlabs.org
Subject: Re: [RFC] Device Tree Overlays Proposal (Was Re: capebus moving omap_devices to mach-omap2)
Date: Tue, 13 Nov 2012 11:05:15 +1100 [thread overview]
Message-ID: <20121113000515.GP4696@truffula.fritz.box> (raw)
In-Reply-To: <CACxGe6v7q2=Dxn6BE_V-w9CEKxAsZ6zQd5Uqm4TeYGYCCu76cg@mail.gmail.com>
On Fri, Nov 09, 2012 at 09:08:14PM +0000, Grant Likely wrote:
> On Fri, Nov 9, 2012 at 2:26 AM, David Gibson
> <david@gibson.dropbear.id.au> wrote:
> >> Summary points:
> >> - Create an FDT overlay data format and usage model
> >> - SHALL reliable resolve or validate of phandles between base and
> >> overlay trees
> >
> > So, I'm not at all clear on what this proposed phandle validation
> > would involve. I'm also not convinced it's as necessary as you
> > think, more on that below.
>
> Simply this: I'm taking this example from the omap3-beagle-xm.dts. It
> has the following stanza which is currently rolled into the resulting
> .dtb when compiled.
>
> &i2c1 {
> clock-frequency = <2600000>;
>
> twl: twl@48 {
> reg = <0x48>;
> interrupts = <7>; /* SYS_NIRQ cascaded to intc */
> interrupt-parent = <&intc>;
>
> vsim: regulator-vsim {
> compatible = "ti,twl4030-vsim";
> regulator-min-microvolt = <1800000>;
> regulator-max-microvolt = <3000000>;
> };
>
> twl_audio: audio {
> compatible = "ti,twl4030-audio";
> codec {
> };
> };
> };
> };
>
> However, if it were compiled into a separate dtb overlay it might look
> like this:
>
> / {
> .readonly;
> ocp {
> .readonly;
> interrupt-controller@48200000 {
> phandle = <0x1234>; /* EXPECTED PHANDLE */
> .readonly;
> };
> i2c@48070000 {
> .must-exist;
> clock-frequency = <2600000>;
>
> twl@48 {
> reg = <0x48>;
> interrupts = <7>;
> interrupt-parent = <0x1234>; /* RESOLVED PHANDLE */
>
> vsim: regulator-vsim {
> compatible = "ti,twl4030-vsim";
> regulator-min-microvolt = <1800000>;
> regulator-max-microvolt = <3000000>;
> };
>
> twl_audio: audio {
> compatible = "ti,twl4030-audio";
> codec {
> };
> };
> };
> };
> };
> };
>
> Notice I've included the intc node and it's phandle. By phandle
> validation I merely mean that when applying an overly the firmware or
> kernel must verify that the phandles in the overlay match the phandle
> in the base tree. If they don't match, then refuse to apply the
> overhead. This approach avoids the need to find and fixup phandles in
> the overlay. And if the phandle is generated from a hash of the
> full_name, then the resulting phandle will only change if the node
> moves.
>
> Similarly, at application time it should be verified that the nodes
> with a .readonly or .must-exist property could be verified to actually
> exist before attempting to apply the overlay. I used two different
> properties with the idea that only certain nodes would need to be
> modified... exactly what the policies should be is yet to be
> determined.
Ok, I see. I really don't like it much, but I understand.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
next prev parent reply other threads:[~2012-11-13 0:30 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
2012-11-05 21:40 ` Tabi Timur-B04825
2012-11-05 23:22 ` Tony Lindgren
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 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
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
2012-11-07 10:19 ` Benoit Cousson
2012-11-07 11:02 ` Pantelis Antoniou
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
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
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>
2012-11-10 3:36 ` Joel A Fernandes
2012-11-12 12:48 ` Pantelis Antoniou
2012-11-13 2:28 ` David Gibson
2012-11-06 22:37 ` Stephen Warren
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
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
2012-11-12 12:10 ` Pantelis Antoniou
2012-11-12 16:52 ` Stephen Warren
2012-11-13 7:25 ` David Gibson
2012-11-13 8:09 ` Pantelis Antoniou
2012-11-13 12:24 ` Grant Likely
2012-11-13 13:38 ` Pantelis Antoniou
2012-11-15 4:57 ` David Gibson
2012-11-13 17:10 ` Stephen Warren
2012-11-13 23:30 ` David Gibson
2012-11-14 0:00 ` Pantelis Antoniou
2012-11-13 16:57 ` Stephen Warren
2012-11-13 18:10 ` Mitch Bradley
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
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
2012-11-09 2:26 ` David Gibson
2012-11-09 15:40 ` Pantelis Antoniou
2012-11-13 0:03 ` David Gibson
2012-11-09 21:08 ` Grant Likely
2012-11-13 0:05 ` David Gibson [this message]
2012-11-09 21:42 ` Grant Likely
2012-11-13 1:05 ` David Gibson
2012-11-13 5:22 ` Stephen Warren
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
2012-11-09 23:14 ` Stephen Warren
2012-11-09 23:06 ` Stephen Warren
2012-11-09 23:32 ` Grant Likely
2012-11-12 11:03 ` Koen Kooi
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