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Commit 18eab855 authored by Venkatesh Pallipadi's avatar Venkatesh Pallipadi Committed by Len Brown
Browse files

ACPI: Enable C3 even when PM2_control is zero 



On systems that do not have pm2_control_block, we cannot really use
ARB_DISABLE before C3. We used to disable C3 totally on such systems.

To be compatible with Windows, we need to enable C3 on such systems now.
We just skip ARB_DISABLE step before entering the C3-state and assume
hardware is handling things correctly. Also, ACPI spec is not clear
about pm2_control is _needed_ for C3 or not.

We have atleast one system that need this to enable C3.

Signed-off-by: default avatarVenkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent 33ce2033

drivers/acpi/processor_idle.c

+15 −5
Original line number Diff line number Diff line
@@ -488,7 +488,17 @@ static void acpi_processor_idle(void) 


	case ACPI_STATE_C3:



		if (pr->flags.bm_check) {

		/*

		 * disable bus master

		 * bm_check implies we need ARB_DIS

		 * !bm_check implies we need cache flush

		 * bm_control implies whether we can do ARB_DIS

		 *

		 * That leaves a case where bm_check is set and bm_control is

		 * not set. In that case we cannot do much, we enter C3

		 * without doing anything.

		 */

		if (pr->flags.bm_check && pr->flags.bm_control) {

			if (atomic_inc_return(&c3_cpu_count) ==

			    num_online_cpus()) {

				/*
@@ -497,7 +507,7 @@ static void acpi_processor_idle(void) 
				 */

				acpi_set_register(ACPI_BITREG_ARB_DISABLE, 1);

			}

		} else {

		} else if (!pr->flags.bm_check) {

			/* SMP with no shared cache... Invalidate cache  */

			ACPI_FLUSH_CPU_CACHE();

		}
@@ -509,7 +519,7 @@ static void acpi_processor_idle(void) 
		acpi_cstate_enter(cx);

		/* Get end time (ticks) */

		t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);

		if (pr->flags.bm_check) {

		if (pr->flags.bm_check && pr->flags.bm_control) {

			/* Enable bus master arbitration */

			atomic_dec(&c3_cpu_count);

			acpi_set_register(ACPI_BITREG_ARB_DISABLE, 0);
@@ -959,9 +969,9 @@ static void acpi_processor_power_verify_c3(struct acpi_processor *pr, 
	if (pr->flags.bm_check) {

		/* bus mastering control is necessary */

		if (!pr->flags.bm_control) {

			/* In this case we enter C3 without bus mastering */

			ACPI_DEBUG_PRINT((ACPI_DB_INFO,

					  "C3 support requires bus mastering control\n"));

			return;

				"C3 support without bus mastering control\n"));

		}

	} else {

		/*