Quoting Uwe Kleine-König (2023-03-29 13:46:32)
> > > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> > > index c3c3f8c07258..356119a7e5fe 100644
> > > --- a/drivers/clk/clk.c
> > > +++ b/drivers/clk/clk.c
> > > [...]
> > > @@ -1352,12 +1354,17 @@ static void __init clk_disable_unused_subtree(struct clk_core *core)
> > > * back to .disable
> > > */
> > > if (clk_core_is_enabled(core)) {
> > > - trace_clk_disable(core);
> > > - if (core->ops->disable_unused)
> > > - core->ops->disable_unused(core->hw);
> > > - else if (core->ops->disable)
> > > - core->ops->disable(core->hw);
> > > - trace_clk_disable_complete(core);
> > > + if (clk_unused_keep_on) {
> > > + pr_warn("Keep unused clk \"%s\" on\n", core->name);
> > > + clk_unused_keep_on -= 1;
> > > + } else {
> > > + trace_clk_disable(core);
> >
> > We have trace_clk_disable() here. Can you have this tracepoint print to
> > the kernel log and watch over serial console? That would be faster than
> > bisecting.
>
> Well no, that doesn't work for all the problems where
> clk_ignore_unused=7 could be useful. Consider that e.g. you know that
> eth0 is broken, but with clk_ignore_unused is works. So one of the (say)
> 25 nominally unused clks are required for eth0. But it's not possible to
> test the network after each of the 25 clk_disable()s. Unless I'm missing
> something and you can hook a userspace action on a trace line?!
In that case it sounds like you want to compile the kernel with the
support for enabling clks from debugfs. Can you use that?
