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From: Ulf Hansson <ulf.hansson@linaro.org>
Date: Mon, 30 Oct 2017 16:40:07 +0100
Message-ID: <CAPDyKFpCf50XRowGe3X5KpmhKrb99NTxOUQtz4RN4aemAVAJCA@mail.gmail.com>
Subject: Re: [RESEND PATCH v2 1/2] soc: amlogic: add Meson GX VPU Domains driver
To: Neil Armstrong <narmstrong@baylibre.com>
Cc: Kevin Hilman <khilman@baylibre.com>, Carlo Caione <carlo@caione.org>,
        linux-pm@lists.linux-foundation.org,
        "open list:ARM/Amlogic Meson..." <linux-amlogic@lists.infradead.org>,
        "linux-arm-kernel@lists.infradead.org" 
        <linux-arm-kernel@lists.infradead.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
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Hi Neil,

[...]

> +
> +       pm_genpd_init(&vpu_hdmi_pd.genpd, &simple_qos_governor,
> +                     meson_gx_pwrc_vpu_get_power(&vpu_hdmi_pd));
> +

This means that you may initialize the genpd in powered on state.

For that scenario, I think you will hit a clock unprepare/disable
in-balance issue when genpd calls your ->power_off() callback, simply
because you didn't call clk_prepare_enable() for the clocks first.

[...]

Kind regards
Uffe