Re: [RFC PATCH 1/1] x86: msr: add new 'msr_pkg_cst_config_control.h' header

[Artem Bityutskiy <dedekind1@gmail.com>]

Hi Rafael,

sorry for so long delay.

On Thu, 2025-02-27 at 21:01 +0100, Rafael J. Wysocki wrote:
> static inline unsigned long long
> msr_pkg_cst_config_c1_auto_demote(bool set, unsigned long long
> other_bits)
> {
>         unsigned long long val, newval;
> 
>         rdmsrl(MSR_PKG_CST_CONFIG_CONTROL, val);
> 
>         if (set)
>                 newval |= NHM_C1_AUTO_DEMOTE | other_bits;
>         else
>                 newval &= ~(NHM_C1_AUTO_DEMOTE | other_bits);
> 
>         wrmsrl(MSR_PKG_CST_CONFIG_CONTROL, newval);
> 
>         return val;
> }

Sure I can do this, sure, thanks. 

One reason why I am still not sure it is worth it is because the 
"lincroft" platform the C1 demotion bit is

#define ATM_LNC_C6_AUTO_DEMOTE		(1UL << 25)

so this function does not seem to be universal enough to cover this code in
intel_idle.c:

static void auto_demotion_disable(void)
{
	unsigned long long msr_bits;

	wrmsrl_pkg_cst_config_control(false, auto_demotion_disable_flags);
	msr_bits = rdmsrl_pkg_cst_config_control();
	msr_bits &= ~auto_demotion_disable_flags;
	wrmsrl_pkg_cst_config_control(msr_bits);
}

Artem.