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@xxxxxxxxxxxxxxxxxxxxxxx> > > 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 -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
