Re: Unexplained long boot delays [Was Re: [GIT PULL] RCU changes for v6.9]

[Linus Torvalds <torvalds@linux-foundation.org>]

On Wed, 13 Mar 2024 at 16:29, Florian Fainelli <f.fainelli@gmail.com> wrote:
>
> On this specific commit 7ee988770326fca440472200c3eb58935fe712f6, there
> is a 100% failure for at least 3 devices out of the 16 that are running
> the test.

Hmm.  I have no idea what is going on, and the unimac-mdio probe
function (one of the things that seem to take forever on your setup)
looks fairly simple.

There doesn't even seem to be any timers involved.

That said - one of the things it does is

  unimac_mdio_probe ->
    unimac_mdio_clk_set ->
      clk_prepare_enable

and maybe that's a pattern, because you report that
brcm_pcie_resume_noirq is another problem spot (on resume).

And guess what brcm_pcie_resume_noirq() does?

Yup. clk_prepare_enable().

So I'm wondering if there's some interaction with some clock driver?
That might explain why it shows up on some arm platforms but not
elsewhere.

I may be barking *entirely* up the wrong tree, though. I was just
looking at that unimac probe and going "there's absolutely _nothing_
timer-related here" and that clk thing looked like it might at least
have _some_ relevance.

            Linus