On 12/12/14, 1:19 PM, "Robert Nelson" <[email protected]> wrote:
>On Fri, Dec 12, 2014 at 3:12 PM, John Syn <[email protected]> wrote: >> >> On 12/11/14, 3:23 PM, "Robert Nelson" <[email protected]> wrote: >> >>>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? > >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 > >Regards, > >-- >Robert Nelson >http://www.rcn-ee.com/ > >-- >For more options, visit http://beagleboard.org/discuss >--- >You received this message because you are subscribed to the Google Groups >"BeagleBoard" group. >To unsubscribe from this group and stop receiving emails from it, send an >email to [email protected]. >For more options, visit https://groups.google.com/d/optout. -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
