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Subject: Re: [RFC PATCH 4/9] opp: core: Don't warn if required OPP device does
 not exist
To:     Viresh Kumar <viresh.kumar@linaro.org>
Cc:     linux-arm-kernel@lists.infradead.org,
        Alyssa Rosenzweig <alyssa@rosenzweig.io>,
        Sven Peter <sven@svenpeter.dev>, Marc Zyngier <maz@kernel.org>,
        Mark Kettenis <mark.kettenis@xs4all.nl>,
        Michael Turquette <mturquette@baylibre.com>,
        Stephen Boyd <sboyd@kernel.org>,
        Rob Herring <robh+dt@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
        Viresh Kumar <vireshk@kernel.org>, Nishanth Menon <nm@ti.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        "Rafael J. Wysocki" <rafael@kernel.org>,
        Kevin Hilman <khilman@kernel.org>,
        Ulf Hansson <ulf.hansson@linaro.org>,
        linux-clk@vger.kernel.org, devicetree@vger.kernel.org,
        linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20211011165707.138157-1-marcan@marcan.st>
 <20211011165707.138157-5-marcan@marcan.st>
 <20211012032144.2ltlpat7orrsyr6k@vireshk-i7>
From:   Hector Martin <marcan@marcan.st>
Message-ID: <b7cd51ec-38e5-11d8-5193-1170c9d60ac9@marcan.st>
Date:   Tue, 12 Oct 2021 14:34:09 +0900
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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@marcan.st)
Public Key: https://mrcn.st/pub