linux-kernel - [PATCH, RFC] Re: TSC features, ...

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Message-Id: <200906150925.31854.lkml@morethan.org>
Date:	Mon, 15 Jun 2009 09:25:29 -0500
From:	"Michael S. Zick" <lkml@...ethan.org>
To:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Cc:	Harald Welte <HaraldWelte@...tech.com>,
	Dave Jones <davej@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH, RFC] Re: TSC features, ...

On Mon June 15 2009, Michael S. Zick wrote:
> On Mon June 8 2009, Linus Torvalds wrote:
> > 
> > Hmm. This all really should be just
> > 
> > 	static int check_est_cpu(unsigned int cpuid)
> > 	{
> > 		struct cpuinfo_x86 *cpu = &cpu_data(cpuid);
> > 		return cpu_has(cpu, X86_FEATURE_EST);
> > 	}
> > 
> > I suspect, with no vendor tests. That's the whole _point_ of CPU features, 
> > after all.
> > 
> 

Like this;
Let the vendor's cpu setup code be responsible for getting the
feature flag correct:

diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index 10a2d91..daea6a9 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -244,22 +244,12 @@ int acpi_processor_resume(struct acpi_device * device)
 #if defined (CONFIG_GENERIC_TIME) && defined (CONFIG_X86)
 static void tsc_check_state(int state)
 {
-       switch (boot_cpu_data.x86_vendor) {
-       case X86_VENDOR_AMD:
-       case X86_VENDOR_INTEL:
-               /*
-                * AMD Fam10h TSC will tick in all
-                * C/P/S0/S1 states when this bit is set.
-                */
-               if (boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
-                       return;
+       if (boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
+               return;

-               /*FALL THROUGH*/
-       default:
-               /* TSC could halt in idle, so notify users */
-               if (state > ACPI_STATE_C1)
-                       mark_tsc_unstable("TSC halts in idle");
-       }
+       /* TSC could halt in idle, so notify users */
+       if (state > ACPI_STATE_C1)
+               mark_tsc_unstable("TSC halts in idle");
 }
 #else
 static void tsc_check_state(int state) { return; }

Mike
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