Re: [PATCH] clk: add new Kconfig to control default behavior of disabling unused clocks

[Abel Vesa]

On 26-03-17 08:30:24, Maxime Ripard wrote:
> Hi,
> 
> On Mon, Mar 16, 2026 at 06:33:45PM -0400, Brian Masney wrote:
> > At the 2023 Linux Plumbers Conference in Richmond VA, there was a
> > discussion about how large number of systems need to boot with
> > clk_ignore_unused. Per the discussions at the conference, the existing
> > behavior in the clk core is broken, and there is a desire to completely
> > remove this functionality.
> 
> Broken how?
> 
> clk_ignore_unused is to a point where it's seriously cargo-culted and
> documented as a silver bullet, when in reality it's just a debug tool
> for broken drivers, and the driver must be fixed.
> 
> But nobody is actually fixing it.
> 
> See
> https://fedoraproject.org/wiki/Changes/Automatic_DTB_selection_for_aarch64_EFI_systems#How_To_Test
> for example. The affected clock could be marked as CLK_IS_CRITICAL, and
> fedora wouldn't have to package anything, change anything, etc. But no,
> the problem is clk_ignore_unused.

Nope. Don't ever mark clocks as critical unless system crashes without
them.

Here is an example or why clocks cannot be marked as critical but need
to be kept by the clk_ignore_unused: display driver probes later.
If you mark it as critical you just made the clock stay enabled even
when display is off.

And this is just one example.