Re: [PATCH] pmdomain: arm: Fix debugfs node creation failure

From: Sibi Sankar
Date: Mon Jul 08 2024 - 06:07:51 EST




On 7/5/24 18:34, Sudeep Holla wrote:
On Fri, Jul 05, 2024 at 09:16:29AM +0530, Sibi Sankar wrote:

On 7/4/24 16:02, Sudeep Holla wrote:

If there are 2 perf domains for a device or group of devices, there must
be something unique about each of these domains. Why can't the firmware
specify the uniqueness or the difference via the name?

The example above seems firmware is being just lazy to update it. Also
for the user/developer/debugger, the unique name might be more useful
than just this number.

So please use the name(we must now have extended name if 16bytes are less)
to provide unique names. Please stop working around such silly firmware
bugs like this, it just makes using debugfs for anything useful harder.

This is just meant to address firmware that are already out in the wild.
That being said I don't necessarily agree with the patch either since
it's penalizing firmware that actually uses a proper name by appending
something inherently less useful to it. Since, the using of an unique
domain name isn't required by the spec, the need for it goes under the radar
for vendors. Mandating it might be the right thing to do since
the kernel seems inherently expect that.


Well I would love if spec authors can agree and mandate this. But this is
one of those things I can't argue as I don't necessarily agree with the
argument. There are 2 distinct/unique domains but firmware authors ran out
of unique names for them or just can't be bothered to care about it.

They can't run out of characters as well in above examples, firmware can
add some useless domain ID in the name if they can't be bothered or creative.

So I must admit I can't be bothered as well with that honestly.

Okay, I guess the conclusion is that if the firmware vendors
don't care enough to provide unique names, they get to live
without those debugfs nodes.

Do we really want to register/expose scmi perf power-domains used by
the CPU nodes? Given that scmi-cpufreq doesn't consume these power
domains and can be voted upon by another consumer, wouldn't this cause
a disconnect?

-Sibi

--
Regards,
Sudeep