[PATCH 017/112] ACPI: add "processor.ignore_ppc" hook to workaround BIOS _PPC weirdness

Len Brown
2008-02-07T09:35:40Z

From: Thomas Renninger <trenn@suse.de>

There have been fixes using _PPC, which seem to unhide a problem
on HP nx6125 (double cpufreq switch freezes the machine for
several seconds).

This one should provide a workaround for the nx6125 and for
possible other machines that show any weird _PPC behaviour.

Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>
---
drivers/acpi/processor_perflib.c | 16 +++++++++++++++-
1 files changed, 15 insertions(+), 1 deletions(-)

diff --git a/drivers/acpi/processor_perflib.c b/drivers/acpi/processor_perflib.c
index 463b024..f32010b 100644
--- a/drivers/acpi/processor_perflib.c
+++ b/drivers/acpi/processor_perflib.c
@@ -60,6 +60,11 @@ static DEFINE_MUTEX(performance_mutex);
* policy is adjusted accordingly.
*/

+static unsigned int ignore_ppc = 0;
+module_param(ignore_ppc, uint, 0644);
+MODULE_PARM_DESC(ignore_ppc, "If the frequency of your machine gets wrongly" \
+ "limited by BIOS, this should help");
+
#define PPC_REGISTERED 1
#define PPC_IN_USE 2

@@ -72,6 +77,9 @@ static int acpi_processor_ppc_notifier(struct notifier_block *nb,
struct acpi_processor *pr;
unsigned int ppc = 0;

+ if (ignore_ppc)
+ return 0;
+
mutex_lock(&performance_mutex);

if (event != CPUFREQ_INCOMPATIBLE)
@@ -130,7 +138,13 @@ static int acpi_processor_get_platform_limit(struct acpi_processor *pr)

int acpi_processor_ppc_has_changed(struct acpi_processor *pr)
{
- int ret = acpi_processor_get_platform_limit(pr);
+ int ret;
+
+ if (ignore_ppc)
+ return 0;
+
+ ret = acpi_processor_get_platform_limit(pr);
+
if (ret < 0)
return (ret);
else
--
1.5.4.23.gef5b9