v3.19-rc0 & overlays...

So if your watching git:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=7ef58b32f571bffb7763c6252ad7527562081f34

- OF_RECONFIG notifiers for SPI, I2C and Platform devices. Those
subsystems can now respond to live changes to the device tree.
- CONFIG_OF_OVERLAY method for applying live changes to the device tree

Regards,

Hurray!

So if your watching git:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id
=7ef58b32f571bffb7763c6252ad7527562081f34

- OF_RECONFIG notifiers for SPI, I2C and Platform devices. Those
subsystems can now respond to live changes to the device tree.
- CONFIG_OF_OVERLAY method for applying live changes to the device tree

Yeah, this is really good news. BTW, what is the mechanism to update the
devicetree from user space? Is this done via sysfs like capemanager?

Regards,
John

It's thru: "configfs", Pantelis's patch is here:

http://www.spinics.net/lists/devicetree/msg61079.html

<docs in patch>

+Howto use the configfs overlay interface.

So if your watching git:

Merge tag 'usb-6.7-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb - kernel/git/torvalds/linux.git - Linux kernel source tree?
id
=7ef58b32f571bffb7763c6252ad7527562081f34

- OF_RECONFIG notifiers for SPI, I2C and Platform devices. Those
subsystems can now respond to live changes to the device tree.
- CONFIG_OF_OVERLAY method for applying live changes to the device tree

Yeah, this is really good news. BTW, what is the mechanism to update the
devicetree from user space? Is this done via sysfs like capemanager?

It's thru: "configfs", Pantelis's patch is here:

http://www.spinics.net/lists/devicetree/msg61079.html

<docs in patch>

+Howto use the configfs overlay interface.
+
+A device-tree configfs entry is created in /config/device-tree/overlays
+and and it is manipulated using standard file system I/O.
+Note that this is a debug level interface, for use by developers and
+not necessarily something accessed by normal users due to the
+security implications of having direct access to the kernel's device
tree.
+
+* To create an overlay you mkdir the directory:
+
+ # mkdir /config/device-tree/overlays/foo
+
+* Either you echo the overlay firmware file to the path property file.
+
+ # echo foo.dtbo >/config/device-tree/overlays/foo/path
+
+* Or you cat the contents of the overlay to the dtbo file
+
+ # cat foo.dtbo >/config/device-tree/overlays/foo/dtbo
+
+The overlay file will be applied, and devices will be created/destroyed
+as required.
+
+To remove it simply rmdir the directory.
+
+ # rmdir /config/device-tree/overlays/foo
+
+The rationalle of the dual interface (firmware & direct copy) is that
each is
+better suited to different use patterns. The firmware interface is what's
+intended to be used by hardware managers in the kernel, while the
copy interface
+make sense for developers (since it avoids problems with namespaces).

That is really nice.

Regards,
John