1 files changed, 18 insertions, 0 deletions

diff --git a/arch/i386/kernel/cpu/cpufreq/longhaul.c b/arch/i386/kernel/cpu/cpufreq/longhaul.c
index 504c6c9107d5..ff4829666472 100644
--- a/arch/i386/kernel/cpu/cpufreq/longhaul.c
+++ b/arch/i386/kernel/cpu/cpufreq/longhaul.c
@@ -254,6 +254,8 @@ static void longhaul_setstate(unsigned int clock_ratio_index)
         struct cpufreq_freqs freqs;
         unsigned long flags;
         unsigned int pic1_mask, pic2_mask;
+        u32 bm_status = 0;
+        u32 bm_timeout = 100000;
 
         if (old_ratio == clock_ratio_index)
                 return;
@@ -284,6 +286,18 @@ static void longhaul_setstate(unsigned int clock_ratio_index)
         outb(0xFF,0xA1);        /* Overkill */
         outb(0xFE,0x21);        /* TMR0 only */
 
+        /* Wait while PCI bus is busy. */
+        if (longhaul_flags & USE_NORTHBRIDGE
+            || ((pr != NULL) && pr->flags.bm_control)) {
+                acpi_get_register(ACPI_BITREG_BUS_MASTER_STATUS, &bm_status);
+                while (bm_status && bm_timeout) {
+                        acpi_set_register(ACPI_BITREG_BUS_MASTER_STATUS, 1);
+                        bm_timeout--;
+                        acpi_get_register(ACPI_BITREG_BUS_MASTER_STATUS,
+                                          &bm_status);
+                }
+        }
+
         if (longhaul_flags & USE_NORTHBRIDGE) {
                 /* Disable AGP and PCI arbiters */
                 outb(3, 0x22);
@@ -335,6 +349,10 @@ static void longhaul_setstate(unsigned int clock_ratio_index)
 
         freqs.new = calc_speed(longhaul_get_cpu_mult());
         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
+
+        if (!bm_timeout)
+                printk(KERN_INFO PFX "Warning: Timeout while waiting for "
+                        "idle PCI bus.\n");
 }
 
 /*