Re: [PATCH] clk: Warn (and therefore taint the kernel) on clk_ignore_unused

[Stephen Boyd <sboyd@kernel.org>]

Quoting Dmitry Baryshkov (2025-03-03 15:17:21)
> On Tue, 4 Mar 2025 at 00:16, Florian Fainelli
> <florian.fainelli@broadcom.com> wrote:
> >
> > On 3/3/25 14:48, Stephen Boyd wrote:
> > > Quoting Konrad Dybcio (2025-02-01 08:52:30)
[...]
> > >>
> > >> The clock subsystem plays a crucial part in this quest, as even if
> > >> the clock controllers themselves don't draw a lot of power when on
> > >> (comparatively), improper description of clock requirements has been
> > >> the #1 cause of incomplete/incorrect devicetree bindings in my
> > >> experience.
> > >
> > > 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.
> 

Maybe we would be better off with a config option that removes the clk
ignore unused ability entirely. Then you can have a kernel config check
somewhere in the build process that verifies that a user can't even set
the kernel commandline to change the behavior.