linux-kernel - Re: [PATCH v2 3/4] gpio: imx-rpmsg: add imx-rpmsg GPIO driver

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] [day] [month] [year] [list]

Message-ID:
 <PAXPR04MB91857A02029EB7F923C5767F89E3A@PAXPR04MB9185.eurprd04.prod.outlook.com>
Date: Mon, 6 Oct 2025 14:33:50 +0000
From: Shenwei Wang <shenwei.wang@....com>
To: Arnaud POULIQUEN <arnaud.pouliquen@...s.st.com>, Bjorn Andersson
	<andersson@...nel.org>, Mathieu Poirier <mathieu.poirier@...aro.org>, Rob
 Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor
 Dooley <conor+dt@...nel.org>, Shawn Guo <shawnguo@...nel.org>, Sascha Hauer
	<s.hauer@...gutronix.de>, Linus Walleij <linus.walleij@...aro.org>, Bartosz
 Golaszewski <brgl@...ev.pl>
CC: Pengutronix Kernel Team <kernel@...gutronix.de>, Fabio Estevam
	<festevam@...il.com>, Peng Fan <peng.fan@....com>,
	"linux-remoteproc@...r.kernel.org" <linux-remoteproc@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"imx@...ts.linux.dev" <imx@...ts.linux.dev>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>, dl-linux-imx <linux-imx@....com>,
	"openamp-rp@...ts.openampproject.org" <openamp-rp@...ts.openampproject.org>
Subject: Re: [PATCH v2 3/4] gpio: imx-rpmsg: add imx-rpmsg GPIO driver


Hi Arnaud,

> -----Original Message-----
> From: Arnaud POULIQUEN <arnaud.pouliquen@...s.st.com>
> Sent: Monday, October 6, 2025 4:53 AM
> To: Shenwei Wang <shenwei.wang@....com>; Bjorn Andersson
> <andersson@...nel.org>; Mathieu Poirier <mathieu.poirier@...aro.org>; Rob
> Herring <robh@...nel.org>; Krzysztof Kozlowski <krzk+dt@...nel.org>; Conor
> Dooley <conor+dt@...nel.org>; Shawn Guo <shawnguo@...nel.org>; Sascha
> Hauer <s.hauer@...gutronix.de>; Linus Walleij <linus.walleij@...aro.org>;
> Bartosz Golaszewski <brgl@...ev.pl>
> Cc: Pengutronix Kernel Team <kernel@...gutronix.de>; Fabio Estevam
> <festevam@...il.com>; Peng Fan <peng.fan@....com>; linux-
> remoteproc@...r.kernel.org; devicetree@...r.kernel.org; imx@...ts.linux.dev;
> linux-arm-kernel@...ts.infradead.org; linux-kernel@...r.kernel.org; dl-linux-imx
> <linux-imx@....com>; openamp-rp@...ts.openampproject.org
> Subject: [EXT] Re: [PATCH v2 3/4] gpio: imx-rpmsg: add imx-rpmsg GPIO driver
> >> 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.
> > Until then, the GPIO driver will remain in a deferred state, ensuring that all
> consumers of the associated GPIOs are also deferred.
> > 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
> 
> >
> > Thanks,
> > Shenwei
> >
> >> 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