2008-06-07 01:22:43

by Chris Wright

[permalink] [raw]
Subject: [patch 35/50] CPUFREQ: Make acpi-cpufreq more robust against BIOS freq changes behind our back.

-stable review patch. If anyone has any objections, please let us know.
---------------------

From: Venkatesh Pallipadi <[email protected]>

upstream commit: e56a727b023d40d1adf660168883f30f2e6abe0a

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

Signed-off-by: Venkatesh Pallipadi <[email protected]>
Signed-off-by: Thomas Renninger <[email protected]>
Signed-off-by: Dave Jones <[email protected]>
Cc: Thomas Renninger <[email protected]>
Cc: "Anthony L. Awtrey" <[email protected]>
[chrisw: backport to 2.6.25.4]
Signed-off-by: Chris Wright <[email protected]>
---
arch/x86/kernel/cpu/cpufreq/acpi-cpufreq.c | 10 ++++++++++
1 file changed, 10 insertions(+)

--- 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(
{
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(
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;

--