acpi-cpufreq: add strict mode to acpi-cpufreq driver

acpi-cpufreq.c | 27 +++++++++++++++++++++++++++

1 file changed, 27 insertions(+)

strict mode is added to “acpi-cpufreq.c”, that allows to switch to “strict mode”, when after each attempt to set new processor performance the driver checks that frequency has been changed.

Signed-off: Denis Sadykov <[email protected]>
Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi at intel.com>
Signed-off-by: Alexey Starikovskiy <alexey.y.starikovskiy at intel.com>

Index: linux-2.6.17/arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c
===================================================================
@@ -66,6 +66,9 @@
 

static struct cpufreq_driver acpi_cpufreq_driver;

+/* module params */
+static unsigned int use_acpi_strict;
+
static int check_speedstep_cpu(unsigned int cpuid)

{
	struct cpuinfo_x86 *cpu = &cpu_data[cpuid];
@@ -273,6 +276,20 @@
	return (freq);
}

+static unsigned int check_freqs(cpumask_t mask, unsigned int freq,
+ struct acpi_cpufreq_data *data)
+{
+ unsigned int cur_freq;
+ unsigned int i;
+
+ for (i = 0; i < 100; i++) {
+ cur_freq = extract_freq(get_cur_val(mask), data);
+ if (cur_freq == freq)
+ return (1);
+ udelay(10);
+ }
+ return (0);
+}

static int acpi_cpufreq_target(struct cpufreq_policy *policy,
unsigned int target_freq,
@@ -349,6 +366,13 @@

	drv_write(&cmd);

+ if (use_acpi_strict) {
+ if (!check_freqs(cmd.mask, freqs.new, data)) {
+ dprintk("acpi_cpufreq_target failed (%d)\n", policy->cpu);
+ return -EAGAIN;
+ }
+ }
+

	for_each_cpu_mask(i, cmd.mask) {
		freqs.cpu = i;
		cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
@@ -620,6 +644,9 @@
	return;
}

+module_param(use_acpi_strict, uint, 0644); +MODULE_PARM_DESC(use_acpi_strict, "value 0 or non-zero."); +
late_initcall(acpi_cpufreq_init); module_exit(acpi_cpufreq_exit);