Hi Arnaud,

-----Original Message----- From: Arnaud POULIQUEN arnaud.pouliquen@foss.st.com Sent: Monday, October 6, 2025 4:53 AM To: Shenwei Wang shenwei.wang@nxp.com; Bjorn Andersson andersson@kernel.org; Mathieu Poirier mathieu.poirier@linaro.org; Rob Herring robh@kernel.org; Krzysztof Kozlowski krzk+dt@kernel.org; Conor Dooley conor+dt@kernel.org; Shawn Guo shawnguo@kernel.org; Sascha Hauer s.hauer@pengutronix.de; Linus Walleij linus.walleij@linaro.org; Bartosz Golaszewski brgl@bgdev.pl Cc: Pengutronix Kernel Team kernel@pengutronix.de; Fabio Estevam festevam@gmail.com; Peng Fan peng.fan@nxp.com; linux- remoteproc@vger.kernel.org; devicetree@vger.kernel.org; imx@lists.linux.dev; linux-arm-kernel@lists.infradead.org; linux-kernel@vger.kernel.org; dl-linux-imx linux-imx@nxp.com; openamp-rp@lists.openampproject.org Subject: [EXT] Re: [PATCH v2 3/4] gpio: imx-rpmsg: add imx-rpmsg GPIO driver

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Then, the RPMsg device should be probed either by the remote processor using the name service announcement mechanism or if not possible by your remoteproc driver.

The idea is to probe the GPIO driver successfully only after the remote

processor is online and has sent the name service announcement.

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Until then, the GPIO driver will remain in a deferred state, ensuring that all

consumers of the associated GPIOs are also deferred.

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The implementation you provided below does not guarantee that the related consumers will be properly deferred. This is the most important

behavior for a GPIO/I2C controllers.

As long as you keep the GPIO/I2C device as a child of the remote processor node, you should not have deferred probe issues. The|of_platform_populate()|function ensures that the I2C/GPIO devices are probed when the remote processor is started. Calling|devm_gpiochip_add_data|in the RPMsg driver probe should also prevent such issues.

Here, deferred probing is not an issue -it's an intentional feature. We need to ensure that all consumers of the GPIO/I2C controllers remain in the deferred state until the remote processor is fully online.

For instance, consider a regulator node that references a GPIO line from the RPMSG GPIO controller. The regulator will stay in the deferred state until the remote processor comes online and its services are announced and received.

Thanks, Shenwei

Regards, Arnaud

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Thanks, Shenwei

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To better understand my proposal you can have a look to [1]and [2]. Here is another example for an rpmsg_i2c( ST downstream implementation): https://eur01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgit