Re: [PATCH] intel_idle: introduce 'use_acpi_cst' module parameter

[Prarit Bhargava]

On 2/4/25 7:52 AM, David Arcari wrote:
> Hi Artem,
>
> On 2/4/25 7:23 AM, Artem Bityutskiy wrote:
> > Hi David,
> >
> > On Tue, 2025-01-28 at 09:11 -0500, David Arcari wrote:
> >
> > > +The ``use_acpi_cst`` module parameter (recognized by ``intel_idle`` 
> > > if the
> > > +kernel has been configured with ACPI support) can be set to make the 
> > > driver
> > > +ignore the per cpu idle states in lieu of ACPI idle states. 
> > > ``use_acpi_cst``
> > > +has no effect if ``no_acpi`` is set).
> >
> > With this change, there will be three parameters:
> >
> > * no_acpi
> > * use_acpi
> > * use_acpi_cst
> >
> > I would like to make the naming as intuitive as possible. We do not 
> > rename the
> > first 2, but for the 3rd one, I think "force_acpi" would be a better 
> > name. Or
> > perhaps "no_native"?
>
> The problem with force_acpi is it is very similar to force_use_acpi 
> which is what intel_idle.c uses internally:

Given that @Artem is suggesting we change the names of things -- perhaps 
we should fix "force_use_acpi" as well?

P.

> drivers/idle/intel_idle.c:module_param_named(use_acpi, force_use_acpi, 
> bool, 0444);
>
> That said, I am not attached to the 'use_acpi_cst' parameter name.
>
> > * no_acpi - Do not use ACPI at all. Only native mode is available, no 
> > ACPI mode.
> > * use_acpi - No-op in ACPI mode, consult ACPI tables for C-states on/off
> >    status in native mode.
> > * force_acpi (or no_native?) - Work only in ACPI mode, no native mode 
> > available
> >    (ignore all custom tables).
> >
> > Additionally, I think we should enhance the documentation for 
> > 'no_acpi' and
> > 'use_acpi' while we're at it. Otherwise, it is hard to distinguish 
> > between these
> > three options. Would you consider another patch that improves the 
> > documentation
> > for 'no_acpi' and 'use_acpi', and then adds the third parameter?
>
> I'm happy to resubmit. I guess I could use 'no_native' for the new 
> parameter and then update the documentation as you suggest above.
>
> Does that work?
>
> > Thanks, Artem!
>
> Best,
> -DA