From: Gavin Shan <gwshan@linux.vnet.ibm.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Rob Herring <robherring2@gmail.com>,
Gavin Shan <gwshan@linux.vnet.ibm.com>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
Bjorn Helgaas <bhelgaas@google.com>,
Grant Likely <grant.likely@linaro.org>,
"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>
Subject: Re: [PATCH v4 19/21] drivers/of: Support adding sub-tree
Date: Mon, 4 May 2015 11:30:12 +1000 [thread overview]
Message-ID: <20150504013012.GA15561@gwshan> (raw)
In-Reply-To: <1430534906.7979.85.camel@kernel.crashing.org>
On Sat, May 02, 2015 at 12:48:26PM +1000, Benjamin Herrenschmidt wrote:
>On Sat, 2015-05-02 at 09:29 +1000, Benjamin Herrenschmidt wrote:
>
>> Looking a bit more at it, I don't quite see how I can attach a subtree
>> using that stuff.
>>
>> Instead, each node in the overlay seems to need extra nodes and
>> properties to refer to the original.
>>
>> So the FW would essentially have to create something a lot more complex
>> than just reflattening a bit of its internal tree. For each internal
>> node, it will need to add all those __overlay__ nodes and properties.
>>
>> That is not going to fly for me at all. It's order of magnitudes more
>> complex than the solution we are pursuing.
>>
>> So I think for our use case, we should continue in the direction of
>> having a helper to unflatten a piece of FDT underneath an existing
>> node. I don't like the "HYBRID" stuff though, we should not refer to
>> the original FDT, we should just make them normal dynamic nodes.
Just took a close look on the overlay code. Hopefully I understand
how it works completely. Yeah, there is one questions according to my
understanding. The "overlay" device node should have been in child list
of the device node, who also has the indicator to "target" node. That
means some one else has to create "overlay" node and figure out the
"target" node in advance, then invokes overlay module to apply the
changes. From this perspective, the mechanism is something used to
apply the changes to device-tree, not parsing and create device nodes
from input. It does gurantee all the changes will be applied or none
of them. So I agree on what Ben suggested: to continue the direction
of having a helper to unflatten FDT blobk underneath the existing node,
and "HYBRID" should be replaced with "OF_DYNAMIC".
>
>A bit more thought... if we were to use the overlay stuff, Gavin, what
>we *could* do is add to OPAL FW internal representation a generation
>count to every node and property.
>
>That way we could essentially know whenever something's changed from
>what we flattened originally for the kernel.
>
>We can then create a generic (not PCI specific) call that generates
>an overlay tree for every node and property that has a generation
>count that is newer than what was flattened (or passed by the OS).
>
>It's still a LOT more complex than what we need though...
>
Thanks, Ben. If we really need utilize overlay to support our case,
we need some one to parse the input (device-tree changes) from firmware
and create "overlay" device node and "target" node as I mentioned above.
It's not simpler than the way we had to support our case. I'm not sure
if we really need utilize overlay for our case.
Thanks,
Gavin
WARNING: multiple messages have this Message-ID (diff)
From: Gavin Shan <gwshan@linux.vnet.ibm.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
Gavin Shan <gwshan@linux.vnet.ibm.com>,
Grant Likely <grant.likely@linaro.org>,
Rob Herring <robherring2@gmail.com>,
Bjorn Helgaas <bhelgaas@google.com>,
linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
Subject: Re: [PATCH v4 19/21] drivers/of: Support adding sub-tree
Date: Mon, 4 May 2015 11:30:12 +1000 [thread overview]
Message-ID: <20150504013012.GA15561@gwshan> (raw)
In-Reply-To: <1430534906.7979.85.camel@kernel.crashing.org>
On Sat, May 02, 2015 at 12:48:26PM +1000, Benjamin Herrenschmidt wrote:
>On Sat, 2015-05-02 at 09:29 +1000, Benjamin Herrenschmidt wrote:
>
>> Looking a bit more at it, I don't quite see how I can attach a subtree
>> using that stuff.
>>
>> Instead, each node in the overlay seems to need extra nodes and
>> properties to refer to the original.
>>
>> So the FW would essentially have to create something a lot more complex
>> than just reflattening a bit of its internal tree. For each internal
>> node, it will need to add all those __overlay__ nodes and properties.
>>
>> That is not going to fly for me at all. It's order of magnitudes more
>> complex than the solution we are pursuing.
>>
>> So I think for our use case, we should continue in the direction of
>> having a helper to unflatten a piece of FDT underneath an existing
>> node. I don't like the "HYBRID" stuff though, we should not refer to
>> the original FDT, we should just make them normal dynamic nodes.
Just took a close look on the overlay code. Hopefully I understand
how it works completely. Yeah, there is one questions according to my
understanding. The "overlay" device node should have been in child list
of the device node, who also has the indicator to "target" node. That
means some one else has to create "overlay" node and figure out the
"target" node in advance, then invokes overlay module to apply the
changes. From this perspective, the mechanism is something used to
apply the changes to device-tree, not parsing and create device nodes
from input. It does gurantee all the changes will be applied or none
of them. So I agree on what Ben suggested: to continue the direction
of having a helper to unflatten FDT blobk underneath the existing node,
and "HYBRID" should be replaced with "OF_DYNAMIC".
>
>A bit more thought... if we were to use the overlay stuff, Gavin, what
>we *could* do is add to OPAL FW internal representation a generation
>count to every node and property.
>
>That way we could essentially know whenever something's changed from
>what we flattened originally for the kernel.
>
>We can then create a generic (not PCI specific) call that generates
>an overlay tree for every node and property that has a generation
>count that is newer than what was flattened (or passed by the OS).
>
>It's still a LOT more complex than what we need though...
>
Thanks, Ben. If we really need utilize overlay to support our case,
we need some one to parse the input (device-tree changes) from firmware
and create "overlay" device node and "target" node as I mentioned above.
It's not simpler than the way we had to support our case. I'm not sure
if we really need utilize overlay for our case.
Thanks,
Gavin
next prev parent reply other threads:[~2015-05-04 1:30 UTC|newest]
Thread overview: 184+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-05-01 6:02 [PATCH v4 00/21] PowerPC/PowerNV: PCI Slot Management Gavin Shan
2015-05-01 6:02 ` Gavin Shan
2015-05-01 6:02 ` [PATCH v4 01/21] pci: Add pcibios_setup_bridge() Gavin Shan
2015-05-01 6:02 ` Gavin Shan
2015-05-07 22:12 ` Bjorn Helgaas
2015-05-07 22:12 ` Bjorn Helgaas
2015-05-11 1:59 ` Gavin Shan
2015-05-11 1:59 ` Gavin Shan
2015-05-01 6:02 ` [PATCH v4 02/21] powerpc/powernv: Enable M64 on P7IOC Gavin Shan
2015-05-01 6:02 ` Gavin Shan
2015-05-09 0:18 ` Alexey Kardashevskiy
2015-05-09 0:18 ` Alexey Kardashevskiy
2015-05-11 4:37 ` Gavin Shan
2015-05-11 4:37 ` Gavin Shan
2015-05-01 6:02 ` [PATCH v4 03/21] powerpc/powernv: M64 support improvement Gavin Shan
2015-05-01 6:02 ` Gavin Shan
2015-05-09 10:24 ` Alexey Kardashevskiy
2015-05-09 10:24 ` Alexey Kardashevskiy
2015-05-11 4:47 ` Gavin Shan
2015-05-11 4:47 ` Gavin Shan
2015-05-01 6:02 ` [PATCH v4 04/21] powerpc/powernv: Improve IO and M32 mapping Gavin Shan
2015-05-01 6:02 ` Gavin Shan
2015-05-09 10:53 ` Alexey Kardashevskiy
2015-05-09 10:53 ` Alexey Kardashevskiy
2015-05-11 4:52 ` Gavin Shan
2015-05-11 4:52 ` Gavin Shan
2015-05-01 6:02 ` [PATCH v4 05/21] powerpc/powernv: Improve DMA32 segment assignment Gavin Shan
2015-05-01 6:02 ` Gavin Shan
2015-05-01 6:02 ` [PATCH v4 06/21] powerpc/powernv: Create PEs dynamically Gavin Shan
2015-05-01 6:02 ` Gavin Shan
2015-05-09 11:43 ` Alexey Kardashevskiy
2015-05-09 11:43 ` Alexey Kardashevskiy
2015-05-11 4:55 ` Gavin Shan
2015-05-11 4:55 ` Gavin Shan
2015-05-01 6:02 ` [PATCH v4 07/21] powerpc/powernv: Release " Gavin Shan
2015-05-01 6:02 ` Gavin Shan
2015-05-09 12:43 ` Alexey Kardashevskiy
2015-05-09 12:43 ` Alexey Kardashevskiy
2015-05-11 6:25 ` Gavin Shan
2015-05-11 6:25 ` Gavin Shan
2015-05-11 7:02 ` Alexey Kardashevskiy
2015-05-11 7:02 ` Alexey Kardashevskiy
2015-05-12 0:03 ` Gavin Shan
2015-05-12 0:03 ` Gavin Shan
2015-05-12 0:53 ` Alexey Kardashevskiy
2015-05-12 0:53 ` Alexey Kardashevskiy
2015-05-12 1:25 ` Gavin Shan
2015-05-12 1:25 ` Gavin Shan
2015-05-01 6:02 ` [PATCH v4 08/21] powerpc/powernv: Drop pnv_ioda_setup_dev_PE() Gavin Shan
2015-05-01 6:02 ` Gavin Shan
2015-05-09 12:45 ` Alexey Kardashevskiy
2015-05-09 12:45 ` Alexey Kardashevskiy
2015-05-01 6:02 ` [PATCH v4 09/21] powerpc/powernv: Use PCI slot reset infrastructure Gavin Shan
2015-05-01 6:02 ` Gavin Shan
2015-05-09 13:41 ` Alexey Kardashevskiy
2015-05-09 13:41 ` Alexey Kardashevskiy
2015-05-11 6:45 ` Gavin Shan
2015-05-11 6:45 ` Gavin Shan
2015-05-11 7:16 ` Alexey Kardashevskiy
2015-05-11 7:16 ` Alexey Kardashevskiy
2015-05-01 6:02 ` [PATCH v4 10/21] powerpc/powernv: Fundamental reset for PCI bus reset Gavin Shan
2015-05-01 6:02 ` Gavin Shan
2015-05-09 14:12 ` Alexey Kardashevskiy
2015-05-09 14:12 ` Alexey Kardashevskiy
2015-05-11 6:47 ` Gavin Shan
2015-05-11 6:47 ` Gavin Shan
2015-05-11 7:17 ` Alexey Kardashevskiy
2015-05-11 7:17 ` Alexey Kardashevskiy
2015-05-12 0:04 ` Gavin Shan
2015-05-12 0:04 ` Gavin Shan
2015-05-01 6:02 ` [PATCH v4 11/21] powerpc/pci: Don't scan empty slot Gavin Shan
2015-05-01 6:02 ` Gavin Shan
2015-05-01 6:02 ` [PATCH v4 12/21] powerpc/pci: Move pcibios_find_pci_bus() around Gavin Shan
2015-05-01 6:02 ` Gavin Shan
2015-05-01 6:03 ` [PATCH v4 13/21] powerpc/powernv: Introduce pnv_pci_poll() Gavin Shan
2015-05-01 6:03 ` Gavin Shan
2015-05-09 14:30 ` Alexey Kardashevskiy
2015-05-09 14:30 ` Alexey Kardashevskiy
2015-05-11 7:19 ` Gavin Shan
2015-05-11 7:19 ` Gavin Shan
2015-05-01 6:03 ` [PATCH v4 14/21] powerpc/powernv: Functions to get/reset PCI slot status Gavin Shan
2015-05-01 6:03 ` Gavin Shan
2015-05-09 14:44 ` Alexey Kardashevskiy
2015-05-09 14:44 ` Alexey Kardashevskiy
2015-05-01 6:03 ` [PATCH v4 15/21] powerpc/pci: Delay creating pci_dn Gavin Shan
2015-05-01 6:03 ` Gavin Shan
2015-05-09 14:55 ` Alexey Kardashevskiy
2015-05-09 14:55 ` Alexey Kardashevskiy
2015-05-11 7:21 ` Gavin Shan
2015-05-11 7:21 ` Gavin Shan
2015-05-01 6:03 ` [PATCH v4 16/21] powerpc/pci: Create eeh_dev while " Gavin Shan
2015-05-01 6:03 ` Gavin Shan
2015-05-09 15:08 ` Alexey Kardashevskiy
2015-05-09 15:08 ` Alexey Kardashevskiy
2015-05-11 7:24 ` Gavin Shan
2015-05-11 7:24 ` Gavin Shan
2015-05-01 6:03 ` [PATCH v4 17/21] powerpc/pci: Export traverse_pci_device_nodes() Gavin Shan
2015-05-01 6:03 ` Gavin Shan
2015-05-01 6:03 ` [PATCH v4 18/21] powerpc/pci: Update bridge windows on PCI plugging Gavin Shan
2015-05-01 6:03 ` Gavin Shan
2015-05-01 6:03 ` [PATCH v4 19/21] drivers/of: Support adding sub-tree Gavin Shan
2015-05-01 6:03 ` Gavin Shan
2015-05-01 12:54 ` Rob Herring
2015-05-01 12:54 ` Rob Herring
2015-05-01 15:22 ` Benjamin Herrenschmidt
2015-05-01 15:22 ` Benjamin Herrenschmidt
2015-05-01 18:46 ` Rob Herring
2015-05-01 18:46 ` Rob Herring
2015-05-01 22:57 ` Benjamin Herrenschmidt
2015-05-01 22:57 ` Benjamin Herrenschmidt
2015-05-01 23:29 ` Benjamin Herrenschmidt
2015-05-01 23:29 ` Benjamin Herrenschmidt
2015-05-02 2:48 ` Benjamin Herrenschmidt
2015-05-02 2:48 ` Benjamin Herrenschmidt
2015-05-04 1:30 ` Gavin Shan [this message]
2015-05-04 1:30 ` Gavin Shan
2015-05-04 4:51 ` Benjamin Herrenschmidt
2015-05-04 4:51 ` Benjamin Herrenschmidt
2015-05-04 0:23 ` Gavin Shan
2015-05-04 0:23 ` Gavin Shan
[not found] ` <1430521038.7979.70.camel-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>
2015-05-04 16:41 ` Pantelis Antoniou
2015-05-04 16:41 ` Pantelis Antoniou
2015-05-04 16:41 ` Pantelis Antoniou
2015-05-04 21:14 ` Benjamin Herrenschmidt
2015-05-04 21:14 ` Benjamin Herrenschmidt
2015-05-13 23:35 ` Benjamin Herrenschmidt
2015-05-13 23:35 ` Benjamin Herrenschmidt
[not found] ` <1431560124.20218.91.camel-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>
2015-05-14 0:18 ` Rob Herring
2015-05-14 0:18 ` Rob Herring
2015-05-14 0:18 ` Rob Herring
[not found] ` <CAL_JsqKqTa5eg3eOqx3bkeNdO_920WwDiRbQaxwWLEWpCypFmA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-05-14 0:54 ` Benjamin Herrenschmidt
2015-05-14 0:54 ` Benjamin Herrenschmidt
2015-05-14 0:54 ` Benjamin Herrenschmidt
2015-05-14 6:23 ` Pantelis Antoniou
2015-05-14 6:23 ` Pantelis Antoniou
2015-05-14 6:46 ` Benjamin Herrenschmidt
2015-05-14 6:46 ` Benjamin Herrenschmidt
2015-05-14 7:04 ` Pantelis Antoniou
2015-05-14 7:04 ` Pantelis Antoniou
[not found] ` <3988EABE-3DE9-4E1C-9778-22E35138E359-wVdstyuyKrO8r51toPun2/C9HSW9iNxf@public.gmane.org>
2015-05-14 7:14 ` Benjamin Herrenschmidt
2015-05-14 7:14 ` Benjamin Herrenschmidt
2015-05-14 7:14 ` Benjamin Herrenschmidt
2015-05-14 7:19 ` Pantelis Antoniou
2015-05-14 7:19 ` Pantelis Antoniou
2015-05-14 7:19 ` Pantelis Antoniou
[not found] ` <75F026CA-5AC1-4106-B2F0-AB0D006DEF5A-wVdstyuyKrO8r51toPun2/C9HSW9iNxf@public.gmane.org>
2015-05-14 7:25 ` Benjamin Herrenschmidt
2015-05-14 7:25 ` Benjamin Herrenschmidt
2015-05-14 7:25 ` Benjamin Herrenschmidt
2015-05-14 7:29 ` Benjamin Herrenschmidt
2015-05-14 7:29 ` Benjamin Herrenschmidt
[not found] ` <1431588358.4160.42.camel-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>
2015-05-14 7:34 ` Pantelis Antoniou
2015-05-14 7:34 ` Pantelis Antoniou
2015-05-14 7:34 ` Pantelis Antoniou
[not found] ` <D7FC0542-DD1A-428F-8E75-81620C6D83DC-wVdstyuyKrO8r51toPun2/C9HSW9iNxf@public.gmane.org>
2015-05-14 7:47 ` Benjamin Herrenschmidt
2015-05-14 7:47 ` Benjamin Herrenschmidt
2015-05-14 7:47 ` Benjamin Herrenschmidt
2015-05-14 11:02 ` Pantelis Antoniou
2015-05-14 11:02 ` Pantelis Antoniou
2015-05-14 11:02 ` Pantelis Antoniou
2015-05-14 23:25 ` Benjamin Herrenschmidt
2015-05-14 23:25 ` Benjamin Herrenschmidt
[not found] ` <1431564871.4160.8.camel-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>
2015-06-07 7:54 ` Grant Likely
2015-06-07 7:54 ` Grant Likely
[not found] ` <20150607075422.6ECE9C40A12-WNowdnHR2B42iJbIjFUEsiwD8/FfD2ys@public.gmane.org>
2015-06-08 20:57 ` Benjamin Herrenschmidt
2015-06-08 20:57 ` Benjamin Herrenschmidt
[not found] ` <1433797073.4526.163.camel-XVmvHMARGAS8U2dJNN8I7kB+6BGkLq7r@public.gmane.org>
2015-06-08 21:34 ` Grant Likely
2015-06-08 21:34 ` Grant Likely
2015-06-10 6:55 ` Gavin Shan
2015-05-03 23:28 ` Gavin Shan
2015-05-03 23:28 ` Gavin Shan
2015-05-15 1:27 ` Gavin Shan
2015-05-15 1:27 ` Gavin Shan
2015-05-01 6:03 ` [PATCH v4 20/21] powerpc/powernv: Select OF_DYNAMIC Gavin Shan
2015-05-01 6:03 ` Gavin Shan
2015-05-01 6:03 ` [PATCH v4 21/21] pci/hotplug: PowerPC PowerNV PCI hotplug driver Gavin Shan
2015-05-01 6:03 ` Gavin Shan
2015-05-09 15:54 ` Alexey Kardashevskiy
2015-05-09 15:54 ` Alexey Kardashevskiy
2015-05-11 7:38 ` Gavin Shan
2015-05-11 7:38 ` Gavin Shan
2015-05-08 23:59 ` [PATCH v4 00/21] PowerPC/PowerNV: PCI Slot Management Alexey Kardashevskiy
2015-05-08 23:59 ` Alexey Kardashevskiy
2015-05-11 7:40 ` Gavin Shan
2015-05-11 7:40 ` Gavin Shan
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20150504013012.GA15561@gwshan \
--to=gwshan@linux.vnet.ibm.com \
--cc=benh@kernel.crashing.org \
--cc=bhelgaas@google.com \
--cc=devicetree@vger.kernel.org \
--cc=grant.likely@linaro.org \
--cc=linux-pci@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=robherring2@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.