linux-kernel - Re: [PATCH v5 1/5] arm64/dts/qcom/sc7280: remove assigned-clock-rate property for mdp clk

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Message-ID: <CAE-0n51bfqWs8yOiyQ-A_bEQ7CZSqavz8epcFEWYyZxxoRYFHg@mail.gmail.com>
Date:   Tue, 8 Mar 2022 12:05:39 -0800
From:   Stephen Boyd <swboyd@...omium.org>
To:     Vinod Polimera <quic_vpolimer@...cinc.com>,
        devicetree@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, robdclark@...il.com,
        dianders@...omium.org, quic_kalyant@...cinc.com
Subject: Re: [PATCH v5 1/5] arm64/dts/qcom/sc7280: remove assigned-clock-rate
 property for mdp clk

Quoting Vinod Polimera (2022-03-08 08:54:56)
> Kernel clock driver assumes that initial rate is the
> max rate for that clock and was not allowing it to scale
> beyond the assigned clock value.

How? I see ftbl_disp_cc_mdss_mdp_clk_src[] has multiple frequencies and
clk_rcg2_shared_ops so it doesn't look like anything in the clk driver
is preventing the frequency from changing beyond the assigned value.

>
> Drop the assigned clock rate property and vote on the mdp clock as per
> calculated value during the usecase.
>
> Changes in v2:
> - Remove assigned-clock-rate property and set mdp clk during resume sequence.
> - Add fixes tag.
>
> Changes in v3:
> - Remove extra line after fixes tag.(Stephen Boyd)

This changelog should be removed.

>
> Fixes: 62fbdce91("arm64: dts: qcom: sc7280: add display dt nodes")

I thought folks were saying that this is bad to keep? I don't really
mind either way, but I guess it's better to drop the fixes tag because
this is largely a performance improvement?

> Signed-off-by: Vinod Polimera <quic_vpolimer@...cinc.com>
> Reviewed-by: Stephen Boyd <swboyd@...omium.org>