linux-kernel - Re: [PATCH v4 12/16] PM / devfreq: tegra: Reconfigure hardware on governor's restart

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Message-ID: <20190604111738.GL16519@ulmo>
Date:   Tue, 4 Jun 2019 13:17:38 +0200
From:   Thierry Reding <thierry.reding@...il.com>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Jonathan Hunter <jonathanh@...dia.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        linux-pm@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 12/16] PM / devfreq: tegra: Reconfigure hardware on
 governor's restart

On Thu, May 02, 2019 at 02:38:11AM +0300, Dmitry Osipenko wrote:
> Move hardware configuration to governor's start/resume methods.
> This allows to re-initialize hardware counters and reconfigure
> cleanly if governor was stopped/paused. That is needed because we
> are not aware of all hardware changes that happened while governor
> was stopped and the paused state may get out of sync with reality,
> hence it's better to start with a clean slate after the pause. In
> a result there is no memory bandwidth starvation after resume from
> suspend-to-ram that results in display controller underflowing that
> happens on resume because of improper decision made by devfreq about
> the required memory frequency. This change also cleans up code a tad
> by moving hardware-configuration code into a single location.
> 
> Reviewed-by: Chanwoo Choi <cw00.choi@...sung.com>
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>  drivers/devfreq/tegra-devfreq.c | 98 ++++++++++++++-------------------
>  1 file changed, 40 insertions(+), 58 deletions(-)

Acked-by: Thierry Reding <treding@...dia.com>

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