Fix /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq with acpi-cpufreq and ondemand

Hi,

This is 2.6.20 material I think.

Guillaume

As of linux-2.6.20-rc2 using acpi-cpufreq and ondemand on my Pentium M (Asus V6VA laptop) seems broken. /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq contains most of the time 1, sometimes the actual frequency or (rarely) some random value.

The problem seems to come from
http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=7650b281b091f39f5e97f13b45ab3813b1526b65

The attached patch fixes the problem for me.

---

diff -r 5b8ceb2c0e06 arch/i386/kernel/cpu/cpufreq/acpi-cpufreq.c
@@ -440,7 +440,7 @@ static int acpi_cpufreq_target(struct cp
 		cpu_set(policy->cpu, cmd.mask);
 
 	freqs.old = data->freq_table[perf->state].frequency;
-	freqs.new = data->freq_table[next_perf_state].frequency;
+	freqs.new = data->freq_table[next_state].frequency;
 	for_each_cpu_mask(i, cmd.mask) {
 		freqs.cpu = i;
 		cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);

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Hi,

This issue has been fixed in an earlier patch which is in mm right now
http://kernel.org/pub/linux/kernel/people/akpm/patches/2.6/2.6.20-rc2/2.
6.20-rc2-mm1/broken-out/git-cpufreq.patch
[CPUFREQ] Bug fix for acpi-cpufreq and cpufreq_stats oops on
frequency change notification

Can you please check with 2.6.20-rc2-mm1 and report if there are any issues with that kernel.

Thanks,
Venki

Thank you for the notice. 2.6.20-rc2-mm1 works fine.

Regards.

Guillaume