linux-kernel - Re: [RESEND PATCH v2 1/2] soc: amlogic: add Meson GX VPU Domains driver

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Date:   Mon, 30 Oct 2017 17:56:33 +0100
From:   Kevin Hilman <khilman@...libre.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Neil Armstrong <narmstrong@...libre.com>,
        Carlo Caione <carlo@...one.org>,
        linux-pm@...ts.linux-foundation.org,
        "open list\:ARM\/Amlogic Meson..." 
        <linux-amlogic@...ts.infradead.org>,
        "linux-arm-kernel\@lists.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel\@vger.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RESEND PATCH v2 1/2] soc: amlogic: add Meson GX VPU Domains driver

Ulf Hansson <ulf.hansson@...aro.org> writes:

> 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.

Yup, in my testing, I definitely hit this.

Kevin