From: Pantelis Antoniou <panto@antoniou-consulting.com>
To: Ionut Nicu <ioan.nicu.ext@nsn.com>
Cc: Grant Likely <grant.likely@secretlab.ca>,
Rob Herring <robherring2@gmail.com>,
Stephen Warren <swarren@wwwdotorg.org>,
Matt Porter <matt.porter@linaro.org>,
Koen Kooi <koen@dominion.thruhere.net>,
Alison Chaiken <Alison_Chaiken@mentor.com>,
Dinh Nguyen <dinh.linux@gmail.com>, Jan Lubbe <jluebbe@lasnet.de>,
Alexander Sverdlin <alexander.sverdlin@nsn.com>,
Michael Stickel <ms@mycable.de>,
Guenter Roeck <linux@roeck-us.net>,
Dirk Behme <dirk.behme@gmail.com>,
Alan Tull <delicious.quinoa@gmail.com>,
Sascha Hauer <s.hauer@pengutronix.de>,
Michael Bohan <mbohan@codeaurora.org>,
Michal Simek <monstr@monstr.eu>,
Matt Ranostay <mranostay@gmail.com>,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/3] DT: proc: Add runtime overlay interface in /proc
Date: Wed, 6 Nov 2013 11:57:50 +0200 [thread overview]
Message-ID: <FE390E17-5AFB-41AE-9EB3-7EBA3B5D92FF@antoniou-consulting.com> (raw)
In-Reply-To: <527A112F.6070908@nsn.com>
Hi Ionut,
On Nov 6, 2013, at 11:51 AM, Ionut Nicu wrote:
> Hi,
>
> On 05.11.2013 19:41, ext Pantelis Antoniou wrote:
>> Add a runtime interface to /proc to enable generic device tree overlay
>> usage.
>>
>> Two new /proc files are added:
>>
>> /proc/device-tree-overlay & /proc/device-tree-overlay-status
>>
>> /proc/device-tree-overlay accepts a stream of a device tree objects and
>> applies it to the running kernel's device tree.
>>
>> $ cat ~/BB-UART2-00A0.dtbo >device-tree-overlay
>> overlay_proc_release: Applied #2 overlay segments @0
>>
>> /proc/device-tree-overlay-status displays the the overlays added using
>> the /proc interface
>>
>> $ cat device-tree-overlay-status
>> 0: 861 bytes BB-UART2:00A0
>>
>> The format of the status line is
>> <ID>: <SIZE> bytes <part-number>:<version>
>>
>> <ID> is the id of the overlay
>> <SIZE> is the size of the overlay in bytes
>> <part-number>, <version> are (optional) root level properties of the DTBO
>>
>> You can remove an overlay by echoing the <ID> number of the overlay
>> precedded with a '-'
>>
>> So
>> $ echo "-0" >device-tree-overlay-status
>>
>
> Wouldn't it be easier if echo "-BB-UART2-00A0" > device-tree-overlay-status was
> supported also? That way one doesn't need to know the order in which the
> overlays were applied or parse the status file to get the <ID>.
>
Unfortunately no since this is a raw bytestream interface; there is no file
information. The patchset does display any root level part-number & version properties
but that's completely options.
We could standardize in a named root property to use on each overlay, and the part-number &
version are as good as any.
>> Removes the overlay.
>>
>> Note that this seldom works on most platforms since platform_device
>> removal is something that almost never works without extra patches.
>>
>> Signed-off-by: Pantelis Antoniou <panto@antoniou-consulting.com>
>
> It would be very helpful to me if I would have a notification mechanism
> for overlay add and remove operations based on blocking_notifier_call_chain(),.
> This way other drivers can be notified when the dt changes.
>
Yes. Some people expressed interest in something similar.
> But I guess that could be added in the future with another patch.
>
Yep.
> Thanks,
> Ionut
Let's get the basic support in now, and we can fix all of that on later patches.
Regards
-- Pantelis
next prev parent reply other threads:[~2013-11-06 9:58 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-05 18:41 [PATCH 0/3 - V2] Introducing Device Tree Overlays Pantelis Antoniou
2013-11-05 18:41 ` [PATCH 1/3] OF: Introduce Device Tree resolve support Pantelis Antoniou
2013-11-06 15:59 ` Alexander Sverdlin
2013-11-06 16:24 ` Ionut Nicu
2013-11-05 18:41 ` [PATCH 2/3] OF: Introduce DT overlay support Pantelis Antoniou
2013-11-06 16:00 ` Alexander Sverdlin
2013-11-06 16:26 ` Ionut Nicu
2013-11-06 20:41 ` Dinh Nguyen
2013-11-07 7:10 ` Pantelis Antoniou
2013-11-05 18:41 ` [PATCH 3/3] DT: proc: Add runtime overlay interface in /proc Pantelis Antoniou
2013-11-06 9:51 ` Ionut Nicu
2013-11-06 9:57 ` Pantelis Antoniou [this message]
2013-11-06 19:10 ` Rob Herring
2013-11-06 19:24 ` Pantelis Antoniou
2013-11-06 20:16 ` Matt Porter
2013-11-07 7:44 ` Pantelis Antoniou
2013-11-07 23:38 ` delicious quinoa
2013-11-08 7:12 ` Pantelis Antoniou
2013-11-05 19:06 ` [PATCH 0/3 - V2] Introducing Device Tree Overlays Guenter Roeck
2013-11-06 0:15 ` Dinh Nguyen
2013-11-06 8:53 ` Alexander Sverdlin
2013-11-06 19:01 ` Sebastian Andrzej Siewior
2013-11-06 19:08 ` Pantelis Antoniou
2013-11-06 20:31 ` Sebastian Andrzej Siewior
2013-11-06 20:41 ` Sebastian Andrzej Siewior
2013-11-07 7:24 ` Pantelis Antoniou
2013-11-07 7:23 ` Pantelis Antoniou
2013-11-07 9:45 ` Alexander Sverdlin
2013-11-06 19:30 ` Guenter Roeck
2013-11-06 20:38 ` Sebastian Andrzej Siewior
2013-11-06 21:17 ` Guenter Roeck
2013-11-07 7:27 ` Pantelis Antoniou
2013-11-07 19:25 ` Sebastian Andrzej Siewior
2013-11-07 20:06 ` Pantelis Antoniou
2013-11-07 20:46 ` Sebastian Andrzej Siewior
2013-11-07 23:00 ` Guenter Roeck
2013-11-08 7:12 ` Pantelis Antoniou
2013-11-08 8:40 ` Sebastian Andrzej Siewior
2013-11-08 7:09 ` Pantelis Antoniou
2013-11-11 17:04 ` Grant Likely
2013-11-12 8:16 ` Pantelis Antoniou
2013-11-07 22:51 ` Guenter Roeck
2013-11-07 22:22 ` Guenter Roeck
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