[PATCH] Longhaul - Option to disable ACPI C3 support

["Rafał Bilski" <rafalbilski@interia.pl>]

On some motherboards ACPI C3 is available, but it isn't
causing frequency transition on VIA Nehemiah. Longhaul
wasn't working at all earlier, but due to
scaling_cur_speed returning true CPU frequency now, it
looks like CPU is getting stuck at highest frequency
since 2.6.21. I didn't find a reason. Halt is causing 
frequency transition.

Signed-off-by: Rafal Bilski <rafalbilski@interia.pl>
---
 arch/i386/kernel/cpu/cpufreq/longhaul.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/arch/i386/kernel/cpu/cpufreq/longhaul.c b/arch/i386/kernel/cpu/cpufreq/longhaul.c
--- a/arch/i386/kernel/cpu/cpufreq/longhaul.c
+++ b/arch/i386/kernel/cpu/cpufreq/longhaul.c
@@ -75,6 +75,7 @@ static unsigned int longhaul_index;
 
 /* Module parameters */
 static int scale_voltage;
+static int disable_acpi_c3;
 
 #define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, "longhaul", msg)
 
@@ -844,6 +845,9 @@ static int __init longhaul_cpu_init(struct cpufreq_policy *policy)
 		if (cx->address > 0 && cx->latency <= 1000)
 			longhaul_flags |= USE_ACPI_C3;
 	}
+	/* Disable if it isn't working */
+	if (disable_acpi_c3)
+		longhaul_flags &= ~USE_ACPI_C3;
 	/* Check if northbridge is friendly */
 	if (enable_arbiter_disable())
 		longhaul_flags |= USE_NORTHBRIDGE;
@@ -952,6 +956,9 @@ static void __exit longhaul_exit(void)
 	kfree(longhaul_table);
 }
 
+module_param (disable_acpi_c3, int, 0644);
+MODULE_PARM_DESC(disable_acpi_c3, "Don't use ACPI C3 support");
+
 module_param (scale_voltage, int, 0644);
 MODULE_PARM_DESC(scale_voltage, "Scale voltage of processor");
 
-- 



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Ks.Jankowski u Mela Gibsona 

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