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

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Message-ID: <Z9AdICiyaCmzKh-N@bogus>
Date: Tue, 11 Mar 2025 11:23:12 +0000
From: Sudeep Holla <sudeep.holla@....com>
To: Peng Fan <peng.fan@....com>
Cc: "Peng Fan (OSS)" <peng.fan@....nxp.com>,
	Cristian Marussi <cristian.marussi@....com>,
	Sudeep Holla <sudeep.holla@....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 Tue, Mar 11, 2025 at 11:12:45AM +0000, Peng Fan wrote:
> Based on linux-next, I added below node:
>
> +
> +               test@...00000 {
> +                       compatible = "fsl,imx-test";
> +                       power-domains = <&scmi_devpd IMX95_PD_VPU>, <&scmi_perf IMX95_PERF_VPU>;
> +                       power-domain-names = "vpumix", "vpuperf";
> +               };
>
> I not write a driver for it, so just check devlink information from sysfs interface.
>
> From below sys directory, this test device takes scmi_dev.4 and scmi_dev.3 as supplier.
> root@...95evk:/sys/bus/platform/devices/soc:test@...00000# ls
> driver_override  of_node  subsystem                          supplier:scmi_protocol:scmi_dev.4  waiting_for_supplier
> modalias         power    supplier:scmi_protocol:scmi_dev.3  uevent
>
> Checking scmi_dev.4 below, it is scmi cpufreq, not the scmi perf device.
> scmi_dev.3 is correct, it is genpd.
>
> root@...95evk:/sys/bus/platform/devices/soc:test@...00000# cat /sys/bus/scmi_protocol/devices/scmi_dev.4/modalias
> scmi_dev.4:13:cpufreq
> root@...95evk:/sys/bus/platform/devices/soc:test@...00000# cat /sys/bus/scmi_protocol/devices/scmi_dev.3/modalias
> scmi_dev.3:11:genpd
> root@...95evk:/sys/bus/platform/devices/soc:test@...00000#
>
>
> 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.

--
Regards,
Sudeep