linux-kernel - Re: [PATCH 1/4] firmware: arm_scmi: bus: Bypass setting fwnode for scmi cpufreq

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Message-ID: <20250313052309.GA11131@nxa18884-linux>
Date: Thu, 13 Mar 2025 13:23:27 +0800
From: Peng Fan <peng.fan@....nxp.com>
To: Sudeep Holla <sudeep.holla@....com>
Cc: Peng Fan <peng.fan@....com>,
	Cristian Marussi <cristian.marussi@....com>,
	Saravana Kannan <saravanak@...gle.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	Aisheng Dong <aisheng.dong@....com>,
	Fabio Estevam <festevam@...il.com>, Shawn Guo <shawnguo@...nel.org>,
	Jacky Bai <ping.bai@....com>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	Sascha Hauer <s.hauer@...gutronix.de>,
	"arm-scmi@...r.kernel.org" <arm-scmi@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
	"imx@...ts.linux.dev" <imx@...ts.linux.dev>
Subject: Re: [PATCH 1/4] firmware: arm_scmi: bus: Bypass setting fwnode for
 scmi cpufreq

On Wed, Mar 12, 2025 at 11:28:52AM +0000, Sudeep Holla wrote:
>On Wed, Mar 12, 2025 at 10:52:23AM +0000, Sudeep Holla wrote:
>> On Tue, Mar 11, 2025 at 11:23:12AM +0000, Sudeep Holla wrote:
>> > On Tue, Mar 11, 2025 at 11:12:45AM +0000, Peng Fan wrote:
>> > >
>> > > So it is clear that wrong fw_devlink is created, it is because scmi cpufreq device is
>> > > created earlier and when device_add, the below logic makes the fwnode pointer points
>> > > to scmi cpufreq device.
>> > >         if (dev->fwnode && !dev->fwnode->dev) {
>> > >                 dev->fwnode->dev = dev;
>> > >                 fw_devlink_link_device(dev);
>> > >         }
>> > >
>> >
>> > Thanks, looks like simple way to reproduce the issue. I will give it a try.
>> >
>> 
>> I could reproduce but none of my solution solved the problem completely
>> or properly. And I don't like the DT proposal you came up with. I am
>> not inclined to just drop this fwnode setting in the scmi devices and
>> just use of_node.
>>
>
>Sorry for the typo that changes the meaning: s/not/now
>
>I meant "I am now inclined ..", until we figure out a way to make this
>work with devlinks properly.

when you have time, please give a look at
https://github.com/MrVan/linux/commit/b500c29cb7f6f32a38b1ed462e333db5a3e301e4

The upper patch was to follow Cristian's and Dan's suggestion in V2[1] to use
a flag SCMI_DEVICE_NO_FWNODE for scmi device.

I could post out the upper patch as V3 if it basically looks no design flaw.
I will drop the pinctrl patch in v3, considering we are first going
to resolve the fw_devlink issue for cpufreq/devfreq.

[1] https://lore.kernel.org/all/Z6SgFGb4Z88v783c@pluto/

Thanks,
Peng.

>
>-- 
>Regards,
>Sudeep