[CPUFREQ] Make acpi-cpufreq more robust against BIOS freq changes behind our back.

We checked the hardware freq with OS cached freq value in get_cur_freqon_cpu().

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: Thomas Renninger <trenn@suse.de>
Signed-off-by: Dave Jones <davej@redhat.com>

1 files changed, 10 insertions, 0 deletions

diff --git a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
index e2d870de837c..8db8f73503b3 100644
--- a/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
+++ b/arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c
@@ -339,6 +339,7 @@ static unsigned int get_cur_freq_on_cpu(unsigned int cpu)
 {
         struct acpi_cpufreq_data *data = per_cpu(drv_data, cpu);
         unsigned int freq;
+        unsigned int cached_freq;
 
         dprintk("get_cur_freq_on_cpu (%d)\n", cpu);
 
@@ -347,7 +348,16 @@ static unsigned int get_cur_freq_on_cpu(unsigned int cpu)
                 return 0;
         }
 
+        cached_freq = data->freq_table[data->acpi_data->state].frequency;
         freq = extract_freq(get_cur_val(&cpumask_of_cpu(cpu)), data);
+        if (freq != cached_freq) {
+                /*
+                 * The dreaded BIOS frequency change behind our back.
+                 * Force set the frequency on next target call.
+                 */
+                data->resume = 1;
+        }
+
         dprintk("cur freq = %u\n", freq);
 
         return freq;