Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Mon, 5 Sep 2022 10:05:43 +0530
From:   Viresh Kumar <viresh.kumar@linaro.org>
To:     =?utf-8?B?Q2zDqW1lbnQgUMOpcm9u?= <peron.clem@gmail.com>
Cc:     k.konieczny@samsung.com,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Nishanth Menon <nm@ti.com>, Stephen Boyd <sboyd@kernel.org>,
        Viresh Kumar <vireshk@kernel.org>,
        "open list:ALLWINNER CPUFREQ DRIVER" <linux-pm@vger.kernel.org>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Rafael Wysocki <rjw@rjwysocki.net>,
        Mark Brown <broonie@kernel.org>,
        linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 0/2] opp: core: add regulators enable and disable
Message-ID: <20220905043543.huxq7mmpclto2h7k@vireshk-i7>
References: <cover.1589528491.git.viresh.kumar@linaro.org>
 <CAJiuCceftArjKPyiEW8AnT5TtuCJFsRGGA-_8y2zG5GDTxHO4Q@mail.gmail.com>
 <CAJiuCcejjaM=+XWsmOe93idbC8TyyxLj30+Lf+5C=yv=hxT80g@mail.gmail.com>
 <CAJiuCccmVtyHbd7ZvEwmw67aesyPe=eVzSE5z_KjCC5__7brjQ@mail.gmail.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Disposition: inline
Content-Transfer-Encoding: 8bit
In-Reply-To: <CAJiuCccmVtyHbd7ZvEwmw67aesyPe=eVzSE5z_KjCC5__7brjQ@mail.gmail.com>
Precedence: bulk

On 03-09-22, 22:35, Cl?ment P?ron wrote:
> Today, I compiled my kernel without any program requiring GPU
> computing at boot. This makes the dev_pm_opp_set_rate() to never be
> called and so the regulator is not enabled before the regulator
> framework switches off all the regulators that haven't been enabled.
> 
> Unfortunately switching off the GPU regulator makes my board hang..

Why does the board hang? I mean the kernel should boot fine with the
GPU disabled, isn't it ? Or is the regulator shared with some other
critical resource, or something else.

> I'm not sure what is the best approach to fix this.
> 
> Is it required that the dev_pm_opp_set_rate() must be called one time
> at the GPU driver init?

Right now, Yes. And it looks like the right approach as well.

> Panfost already calls devfreq_recommended_opp() and dev_pm_opp_put()
> but that doesn't trigger dev_pm_opp_set_rate().

Can you also point to your code ? Which file are you working on ?

-- 
viresh