linux-kernel - Re: [RFC PATCH 4/9] opp: core: Don't warn if required OPP device does not exist

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Message-ID: <b7cd51ec-38e5-11d8-5193-1170c9d60ac9@marcan.st>
Date:   Tue, 12 Oct 2021 14:34:09 +0900
From:   Hector Martin <marcan@...can.st>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     linux-arm-kernel@...ts.infradead.org,
        Alyssa Rosenzweig <alyssa@...enzweig.io>,
        Sven Peter <sven@...npeter.dev>, Marc Zyngier <maz@...nel.org>,
        Mark Kettenis <mark.kettenis@...all.nl>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...onical.com>,
        Viresh Kumar <vireshk@...nel.org>, Nishanth Menon <nm@...com>,
        Catalin Marinas <catalin.marinas@....com>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Kevin Hilman <khilman@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        linux-clk@...r.kernel.org, devicetree@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 4/9] opp: core: Don't warn if required OPP device does
 not exist

On 12/10/2021 12.21, Viresh Kumar wrote:
> I am not sure why you need this, since _set_required_opps() has this check:
> 
> 	if (unlikely(!required_opp_tables[0]->is_genpd)) {
> 		dev_err(dev, "required-opps don't belong to a genpd\n");
> 		return -ENOENT;
> 	}
> 

The table *is* assigned to a genpd (the memory controller), it's just 
that that genpd isn't actually a parent of the CPU device. Without the 
patch you end up with:

[    3.040060] cpu cpu4: Failed to set performance rate of cpu4: 0 (-19)
[    3.042881] cpu cpu4: Failed to set required opps: -19
[    3.045508] cpufreq: __target_index: Failed to change cpu frequency: -19


-- 
Hector Martin (marcan@...can.st)
Public Key: https://mrcn.st/pub