__clksrc_of_table and "clocksource_probe: no matching clocksources found"

[Valdis Kl=?utf-8?Q?=c4=93?=tnieks]

On Tue, 23 Apr 2019 17:07:14 -0300, Guilherme Costa said:

> From the code, we can see that the message was printed because
> clocksources == 0. This implies that there were no matching nodes on
> the device tree,

Right.

> and that acpi_probe_device_table returned 0 (which is correct, seeing
> that the kernel has no ACPI support).

> This leaves me with two questions:
> 1 - Is this message a problem indicator? I'm assuming it is, because
> it's printed with a pr_crit...

Depends.  Most systems really want a clocksource of some sort.

> 2 - Why is for_each_matching_node_and_match not getting any matches? I
> did not find where __clksrc_of_table is initialized, so maybe it's
> because it is empty?

My first guess is that your hardware has a busted device tree that doesn't
have an entry pointing at any actual valid hardware clock device.  Could
be an incorrect address, or the DT says it's a Frobozz1 clock but the actual
hardware has a Frobozz2 that won't probe using the Frobozz1 driver, or
something else....