linux-kernel - Re: [PATCH 1/9] clk: qcom: gcc-msm8998: Wire up gcc_mmss

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Message-ID: <CAOCk7Nod9a+5EUUWGpso+EBb2dJVLMvjrOoMpqeTcm+L6mxvtQ@mail.gmail.com>
Date:   Thu, 14 Jan 2021 15:33:29 -0700
From:   Jeffrey Hugo <jeffrey.l.hugo@...il.com>
To:     AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...ainline.org>
Cc:     MSM <linux-arm-msm@...r.kernel.org>, konrad.dybcio@...ainline.org,
        marijn.suijten@...ainline.org, martin.botka@...ainline.org,
        phone-devel@...r.kernel.org, lkml <linux-kernel@...r.kernel.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Rob Herring <robh+dt@...nel.org>, linux-clk@...r.kernel.org,
        DTML <devicetree@...r.kernel.org>
Subject: Re: [PATCH 1/9] clk: qcom: gcc-msm8998: Wire up gcc_mmss_gpll0 clock

On Thu, Jan 14, 2021 at 3:13 PM AngeloGioacchino Del Regno
<angelogioacchino.delregno@...ainline.org> wrote:
>
> Il 14/01/21 23:12, Jeffrey Hugo ha scritto:
> > On Sat, Jan 9, 2021 at 6:47 AM AngeloGioacchino Del Regno
> > <angelogioacchino.delregno@...ainline.org> wrote:
> >>
> >> This clock enables the GPLL0 output to the multimedia subsystem
> >> clock controller.
> >>
> >> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...ainline.org>
> >
> > Any reason why you are not also adding the div_clk?
> >
>
> Yes, just one: I haven't tested it... and my devices worked without.
> Perhaps we can add it whenever we find out if something really needs it?

I'm mildly surprised you need to turn on the gate to the PLL0 out, but
not the div_out.  The div_out/div_clk is also fed into every RCG that
exists in the MMCC.

Per the frequency plan the following RCGs require it -

cci
cpp
fd_core
camss_gp[0-1]
jpeg0
mclk[0-3]
csi[0-2]phytimer
dp_gtc
maxi
axi
ahb

Also, I'm very interested in all things 8998, and would generally
appreciate being added to the to: list.