Re: [PATCH] x86/cstate: Allow ACPI C1 FFH MWAIT use on Hygon systems

[Rafael J. Wysocki]

On Fri, May 28, 2021 at 10:44 AM Pu Wen <puwen@xxxxxxxx> wrote:
>
> Hygon systems support the Monitor/Mwait instructions and these can be used
> for ACPI C1 in the same way as on AMD and Intel systems.
>
> The BIOS declares a C1 state in _CST to use FFH and CPUID_Fn00000005_EDX
> is non-zero on Hygon systems.
>
> Allow ffh_cstate_init() to succeed on Hygon systems to default using FFH
> MWAIT instead of HALT for ACPI C1.
>
> Tested successfully on Hygon Fam18h systems.
>
> Signed-off-by: Pu Wen <puwen@xxxxxxxx>
> ---
>  arch/x86/kernel/acpi/cstate.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/acpi/cstate.c b/arch/x86/kernel/acpi/cstate.c
> index 49ae4e1ac9cd..7de599eba7f0 100644
> --- a/arch/x86/kernel/acpi/cstate.c
> +++ b/arch/x86/kernel/acpi/cstate.c
> @@ -197,7 +197,8 @@ static int __init ffh_cstate_init(void)
>         struct cpuinfo_x86 *c = &boot_cpu_data;
>
>         if (c->x86_vendor != X86_VENDOR_INTEL &&
> -           c->x86_vendor != X86_VENDOR_AMD)
> +           c->x86_vendor != X86_VENDOR_AMD &&
> +           c->x86_vendor != X86_VENDOR_HYGON)
>                 return -1;
>
>         cpu_cstate_entry = alloc_percpu(struct cstate_entry);
> --

Applied as 5.14 material, thanks!