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Sun, 04 May 2025 05:33:45 -0700 (PDT) Message-ID: Date: Sun, 4 May 2025 18:03:26 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [Discussion] Global vs Local devicetree overlays for addon board + connector setups To: Herve Codina Cc: xypron.glpk@gmx.de, Jason Kridner , Deepak Khatri , Dhruva Gole , Robert Nelson , Andrew Davis , Geert Uytterhoeven , Greg Kroah-Hartman , David Gibson , Luca Ceresoli , Pantelis Antoniou , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , open list References: <20250430160944.7740d5e9@bootlin.com> Content-Language: en-US From: Ayush Singh In-Reply-To: <20250430160944.7740d5e9@bootlin.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit > 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