diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index af9f2afd72da458abb51bd520034b0fe2987dad4..f8d2b2f47fd4b374c453f3f19ebcea06c62b7250 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -287,10 +287,10 @@ static void acpi_processor_idle(void)
 		pr->power.bm_check_timestamp = jiffies;
 
 		/*
-		 * Apply bus mastering demotion policy.  Automatically demote
+		 * If bus mastering is or was active this jiffy, demote
 		 * to avoid a faulty transition.  Note that the processor
 		 * won't enter a low-power state during this call (to this
-		 * funciton) but should upon the next.
+		 * function) but should upon the next.
 		 *
 		 * TBD: A better policy might be to fallback to the demotion
 		 *      state (use it for this quantum only) istead of
@@ -298,7 +298,8 @@ static void acpi_processor_idle(void)
 		 *      qualification.  This may, however, introduce DMA
 		 *      issues (e.g. floppy DMA transfer overrun/underrun).
 		 */
-		if (pr->power.bm_activity & cx->demotion.threshold.bm) {
+		if ((pr->power.bm_activity & 0x1) &&
+		    cx->demotion.threshold.bm) {
 			local_irq_enable();
 			next_state = cx->demotion.state;
 			goto end;