From 18eab8550397f1f3d4b8b2c5257c88dae25d58ed Mon Sep 17 00:00:00 2001 From: Venkatesh Pallipadi Date: Fri, 15 Jun 2007 19:37:00 -0400 Subject: 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: Venkatesh Pallipadi Signed-off-by: Len Brown --- drivers/acpi/processor_idle.c | 20 +++++++++++++++----- 1 file changed, 15 insertions(+), 5 deletions(-) (limited to 'drivers/acpi/processor_idle.c') diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index ee5759bef945..36dc1d26520a 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -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 { /* -- cgit v1.2.3