linux-kernel - [PATCH 2/6] acpi-cpufreq: Do not load on K8

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Date:	Sun, 20 Jan 2013 11:24:26 +0100
From:	Borislav Petkov <bp@...en8.de>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	André Przywara <andre@...rep.de>,
	Leonid Isaev <lisaev@...il.iu.edu>,
	Tom Gundersen <teg@...m.no>, cpufreq@...r.kernel.org,
	linux-acpi@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Borislav Petkov <bp@...e.de>
Subject: [PATCH 2/6] acpi-cpufreq: Do not load on K8

From: Matthew Garrett <mjg59@...f.ucam.org>

de3ed81d746d ("[CPUFREQ] Change link order of x86 cpufreq modules")
changed cpufreq drivers link order so that powernow-k8 gets loaded first
due to earlier K8s having BIOS bugs.

However, now that acpi-cpufreq supports both AMD and Intel CPUs with HW
P-states, we want to load it first, so that cases where acpi-cpufreq and
powernow-k8 are both built-in and powernow-k8 initializing first, can be
addressed.

So, make sure that even if acpi-cpufreq gets loaded first, it errors out
on K8s and powernow-k8 can be loaded then successfully.

Signed-off-by: Matthew Garrett <mjg59@...f.ucam.org>
Link: http://lkml.kernel.org/r/20130118162347.GA31499@srcf.ucam.org
Signed-off-by: Borislav Petkov <bp@...e.de>
---
 drivers/cpufreq/acpi-cpufreq.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
index 0d048f6a2b23..31b06bbab54c 100644
--- a/drivers/cpufreq/acpi-cpufreq.c
+++ b/drivers/cpufreq/acpi-cpufreq.c
@@ -762,6 +762,12 @@ static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy)
 
 	switch (perf->control_register.space_id) {
 	case ACPI_ADR_SPACE_SYSTEM_IO:
+		if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD &&
+		    boot_cpu_data.x86 == 0xf) {
+			pr_debug("AMD K8 systems must use native drivers.\n");
+			result = -ENODEV;
+			goto err_unreg;
+		}
 		pr_debug("SYSTEM IO addr space\n");
 		data->cpu_feature = SYSTEM_IO_CAPABLE;
 		break;
-- 
1.8.1.rc3

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