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

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Message-ID: <CADLxj5QnVKkRotvKXNFaORqiQJ1oNPm=SpDzWgnOpWgOcXse5Q@mail.gmail.com>
Date: Mon, 2 Jun 2025 20:20:35 -0500
From: Bjorn Andersson <bjorn.andersson@....qualcomm.com>
To: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: Florian Fainelli <florian.fainelli@...adcom.com>,
        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,
        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 5:17 PM Dmitry Baryshkov
<dmitry.baryshkov@...aro.org> wrote:
>
> On Tue, 4 Mar 2025 at 00:16, Florian Fainelli
> <florian.fainelli@...adcom.com> wrote:
> >
> > On 3/3/25 14:48, Stephen Boyd wrote:
> > > Quoting Konrad Dybcio (2025-02-01 08:52:30)
> > >> From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
[..]
> > >
> > > What is a user supposed to do about this warning stack? We already print
> > > a warning. I don't see us dumping the stack when a driver is unfinished
> > > and doesn't implement runtime PM to save power.
> > >
> >
> > Agreed, I don't think this is tremendously helpful given that it does
> > not even tell you what part is incomplete, it's just a broad warning for
> > the entire system.
> >
> > 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?
>
> Unfortunately it's sometimes not that easy. And some developers
> pretend that 'clk_ignore_unused' is a viable way to run the system.
>

A bit late to the discussion, but I think you got that "pretend" part backwards.
Some folks pretend that you can run the Linux kernel on a platform
with clock provider or consumer drivers built as modules without
clk_ignore_unused and have a reliable outcome.

Regards,
Bjorn