linux-kernel - Re: [Discussion] Global vs Local devicetree overlays for addon board + connector setups

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <e05c315d-a907-45f0-8f5c-1c106b05f548@beagleboard.org>
Date: Sun, 4 May 2025 18:03:26 +0530
From: Ayush Singh <ayush@...gleboard.org>
To: Herve Codina <herve.codina@...tlin.com>
Cc: xypron.glpk@....de, Jason Kridner <jkridner@...gleboard.org>,
 Deepak Khatri <lorforlinux@...gleboard.org>, Dhruva Gole <d-gole@...com>,
 Robert Nelson <robertcnelson@...gleboard.org>, Andrew Davis <afd@...com>,
 Geert Uytterhoeven <geert@...ux-m68k.org>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 David Gibson <david@...son.dropbear.id.au>,
 Luca Ceresoli <luca.ceresoli@...tlin.com>,
 Pantelis Antoniou <pantelis.antoniou@...il.com>,
 "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
 <devicetree@...r.kernel.org>, open list <linux-kernel@...r.kernel.org>
Subject: Re: [Discussion] Global vs Local devicetree overlays for addon board
 + connector setups

> It depends on the bus the device is added.
> when an overlay is applied by the kernel, OF_RECONFIG_* events are
> triggered. Some buses handle them:
>
> 	$ git grep OF_RECONFIG_CHANGE
> 	drivers/bus/imx-weim.c: case OF_RECONFIG_CHANGE_ADD:
> 	drivers/bus/imx-weim.c: case OF_RECONFIG_CHANGE_REMOVE:
> 	drivers/gpio/gpiolib-of.c:      case OF_RECONFIG_CHANGE_ADD:
> 	drivers/gpio/gpiolib-of.c:      case OF_RECONFIG_CHANGE_REMOVE:
> 	drivers/i2c/i2c-core-of.c:      case OF_RECONFIG_CHANGE_ADD:
> 	drivers/i2c/i2c-core-of.c:      case OF_RECONFIG_CHANGE_REMOVE:
> 	drivers/of/dynamic.c: * Return: OF_RECONFIG_CHANGE_REMOVE on device going from enabled to
> 	drivers/of/dynamic.c: * disabled, OF_RECONFIG_CHANGE_ADD on device going from disabled to
> 	drivers/of/dynamic.c:   return new_state ? OF_RECONFIG_CHANGE_ADD : OF_RECONFIG_CHANGE_REMOVE;
> 	drivers/of/platform.c:  case OF_RECONFIG_CHANGE_ADD:
> 	drivers/of/platform.c:  case OF_RECONFIG_CHANGE_REMOVE:
> 	drivers/spi/spi.c:      case OF_RECONFIG_CHANGE_ADD:
> 	drivers/spi/spi.c:      case OF_RECONFIG_CHANGE_REMOVE:
> 	include/linux/of.h:     OF_RECONFIG_CHANGE_ADD,
> 	include/linux/of.h:     OF_RECONFIG_CHANGE_REMOVE,


Well, if some bus does handle the event, I guess it is a bug in the 
subsystems that do not? Maybe Greg Kroah-Hartman can clarify the 
expected behavior here? Maybe we are in transition phase here.


Also I guess, feel free to suggest anyone else I should add to this 
discussion thread. I want everyone to come to an understanding regarding 
the fundamental behavior. I have been getting mixed signals in the 
various discussions I have had till now.


Ayush Singh