Fix the problem with incorrect throttling level reported immediately after

reboot. Safter the reboot the TCC is usually in the Automatic mode, in which
reading current performance level is likely to produce bogus results make sure
to switch it to the On-Demand mode and set to some known performance level.
Unfortunately there is no reliable way to check that TCC is in the Automatic
mode. Reading bit 4 of ACPI Thermal Monitor Control Register produces 0
regardless of the current mode.

MFC after:	1 week

1 files changed, 11 insertions, 0 deletions

diff --git a/sys/i386/cpufreq/p4tcc.c b/sys/i386/cpufreq/p4tcc.c
index f65e5d1..e3e0a03 100644
--- a/sys/i386/cpufreq/p4tcc.c
+++ b/sys/i386/cpufreq/p4tcc.c
@@ -223,6 +223,17 @@ setup_p4tcc(void *dummy __unused)
 	p4tcc_economy = tcc[TCC_LEVELS - 1].rlevel;
 	p4tcc_performance = tcc[0].rlevel;
 
+	/*
+	 * Since after the reboot the TCC is usually in the Automatic
+	 * mode, in which reading current performance level is likely to
+	 * produce bogus results make sure to switch it to the On-Demand
+	 * mode and set to some known performance level. Unfortunately
+	 * there is no reliable way to check that TCC is in the Automatic
+	 * mode, reading bit 4 of ACPI Thermal Monitor Control Register
+	 * produces 0 regardless of the current mode.
+	 */
+	p4tcc_setperf(p4tcc_performance);
+
 	p4tcc_percentage = p4tcc_getperf();
 	printf("Pentium 4 TCC support enabled, %d steps from 100%% to %d%%, "
 	    "current performance %u%%\n", nsteps, p4tcc_economy,