linux-kernel - Re: [PATCH 0/3] firmware: arm_scmi: perf/cpufreq: Enable notification only if supported by platform

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Message-ID: <20250611-cherubic-solemn-toucanet-aac5af@sudeepholla>
Date: Wed, 11 Jun 2025 13:17:11 +0100
From: Sudeep Holla <sudeep.holla@....com>
To: "Peng Fan (OSS)" <peng.fan@....nxp.com>
Cc: Cristian Marussi <cristian.marussi@....com>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Viresh Kumar <viresh.kumar@...aro.org>, <arm-scmi@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, <linux-pm@...r.kernel.org>,
	Sudeep Holla <sudeep.holla@....com>, Peng Fan <peng.fan@....com>
Subject: Re: [PATCH 0/3] firmware: arm_scmi: perf/cpufreq: Enable
 notification only if supported by platform

On Wed, Jun 11, 2025 at 03:52:42PM +0800, Peng Fan (OSS) wrote:
> PERFORMANCE_NOTIFY_LIMITS and PERFORMANCE_NOTIFY_LEVEL are optional
> commands. If use these commands on platforms that not support the two,
> there is error log:
>   SCMI Notifications - Failed to ENABLE events for key:13000008 !
>   scmi-cpufreq scmi_dev.4: failed to register for limits change notifier for domain 8
> 

I wonder if it makes sense to quiesce the warnings from the core if the
platform doesn't support notifications. I prefer to not add if notification
supported in all the protocols.

If the interface can return -EOPNOTSUPP(equivalent to SCMI_ERR_SUPPORT),
the caller must handle it appropriately(i.e. continue if it can handle
absence of notification or propagate error).

Cristian, Thoughts/opinions ?

> If platforms not support perf notification, saving some cpu cycles
> by introducing notify_supported ops.
> 

Sure, makes sense to improve where ever possible.

> While at here, patch 1 is a typo fix when doing the patchset.
>

This one looks OK.

-- 
Regards,
Sudeep