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Sun, 04 May 2025 06:00:44 -0700 (PDT) Message-ID: Date: Sun, 4 May 2025 18:30:24 +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: Greg Kroah-Hartman Cc: Herve Codina , xypron.glpk@gmx.de, Jason Kridner , Deepak Khatri , Dhruva Gole , Robert Nelson , Andrew Davis , Geert Uytterhoeven , David Gibson , Luca Ceresoli , Pantelis Antoniou , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , open list References: <20250430160944.7740d5e9@bootlin.com> <2025050448-snipping-flatbed-2752@gregkh> Content-Language: en-US From: Ayush Singh In-Reply-To: <2025050448-snipping-flatbed-2752@gregkh> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 5/4/25 18:20, Greg Kroah-Hartman wrote: > On Sun, May 04, 2025 at 06:03:26PM +0530, Ayush Singh wrote: >>> 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. > Perhaps those other busses just do not have OF devices and so they never > needed to add that functionality to them? > > If they do, then by all means add that code. OF devices are not > possible for many bus types, so there shouldn't be a need to add this to > the driver core, right? > > thanks, > > greg k-h UART devices are pretty common in both Beagle capes and MikroBUS. So I think that will probably need to be added at some point. Ayush Singh