linux-kernel - Re: [PATCH] clk: Warn (and therefore taint the kernel) on clk_ignore

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Message-ID: <CADLxj5SfR90nYWaT19G0wGWM7zw7v91=LBHjZzb0z0+uERcXVQ@mail.gmail.com>
Date: Mon, 2 Jun 2025 20:23:55 -0500
From: Bjorn Andersson <bjorn.andersson@....qualcomm.com>
To: Florian Fainelli <florian.fainelli@...adcom.com>
Cc: Stephen Boyd <sboyd@...nel.org>, Konrad Dybcio <konradybcio@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>,
        Konrad Dybcio <konrad.dybcio@....qualcomm.com>
Subject: Re: [PATCH] clk: Warn (and therefore taint the kernel) on clk_ignore_unused

On Mon, Mar 3, 2025 at 5:16 PM Florian Fainelli
<florian.fainelli@...adcom.com> wrote:
> Assuming you have a clock provided that can be used to turn clocks off,
> and you did not boot with 'clk_ignore_unused' set on the kernel command
> line, then you should discover pretty quickly which driver is not
> managing the clocks as it should no?

clk_ignore_unused affects the behavior of clk_disable_unused(), which
is called at late_initcall() so if either your clock provider or
consumer shows up after this point the disabling of unused clocks will
either not happen (because the clock doesn't yet exist) or it will act
on incomplete data (because the client isn't there to reference it
yet).

Regards,
Bjorn