Re: [PATCH RFT] x86/hpet: Use another crystalball to evaluate HPET usability

On Thu, Sep 30 2021 at 13:38, Rafael J. Wysocki wrote:

...

+static bool __init get_mwait_substates(unsigned int *mwait_substates) +{

•   unsigned int eax, ebx, ecx;
  

•   if (boot_cpu_data.x86_vendor != X86_VENDOR_INTEL)
  

•           return false;
  

•   if (!boot_cpu_has(X86_FEATURE_MWAIT))
  

•           return false;
  

•   if (boot_cpu_data.cpuid_level < CPUID_MWAIT_LEAF)
  

•           return false;
  

•   cpuid(CPUID_MWAIT_LEAF, &eax, &ebx, &ecx, mwait_substates);
  

•   if (!(ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) ||
  

•       !(ecx & CPUID5_ECX_INTERRUPT_BREAK) ||
  

•       !*mwait_substates)
  

•           return false;
  

I would do

return (ecx & CPUID5_ECX_EXTENSIONS_SUPPORTED) && (ecx & CPUID5_ECX_INTERRUPT_BREAK) && *mwait_substates;

And this function could just return the mwait_substates value proper, because returning 0 then would be equivalent to returning 'false' from it as is.

Let me move that substates check into the function which makes it even simpler.

Thanks,

tglx