linux-kernel - Re: [PATCH] drm/panfrost: devfreq: Round frequencies to OPPs

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Date:   Fri, 6 Dec 2019 11:16:48 -0600
From:   Rob Herring <robh@...nel.org>
To:     Steven Price <steven.price@....com>
Cc:     Daniel Vetter <daniel@...ll.ch>, David Airlie <airlied@...ux.ie>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>,
        Alyssa Rosenzweig <alyssa.rosenzweig@...labora.com>,
        dri-devel <dri-devel@...ts.freedesktop.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] drm/panfrost: devfreq: Round frequencies to OPPs

On Mon, Nov 18, 2019 at 11:30 AM Steven Price <steven.price@....com> wrote:
>
> Currently when setting a frequency in panfrost_devfreq_target the
> returned frequency is the actual frequency that the clock driver reports
> (the return of clk_get_rate()). However, where the provided OPPs don't
> precisely match the frequencies that the clock actually achieves devfreq
> will then complain (repeatedly):
>
>   devfreq devfreq0: Couldn't update frequency transition information.
>
> To avoid this change panfrost_devfreq_target() to fetch the opp using
> devfreq_recommened_opp() and not actually query the clock for the
> frequency.
>
> A similar problem exists with panfrost_devfreq_get_cur_freq(), but in
> this case because the function is optional we can just remove it and
> devfreq will fall back to using the previously set frequency.
>
> Fixes: 221bc77914cb ("drm/panfrost: Use generic code for devfreq")
> Signed-off-by: Steven Price <steven.price@....com>
> ---
>  drivers/gpu/drm/panfrost/panfrost_devfreq.c | 19 ++++++-------------
>  1 file changed, 6 insertions(+), 13 deletions(-)

Applied.

Rob