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| author | Venkatesh Pallipadi <venkatesh.pallipadi@intel.com> | 2007-06-15 19:37:00 -0400 |
|---|---|---|
| committer | Len Brown <len.brown@intel.com> | 2007-07-18 21:43:21 -0400 |
| commit | 18eab8550397f1f3d4b8b2c5257c88dae25d58ed (patch) | |
| tree | bc0440ed3e66207fd248163a290b6fcc5c9c2ae6 /drivers/acpi/processor_idle.c | |
| parent | 33ce2033433195ccc1fbad00d26ad854b2ab68d0 (diff) | |
| download | linux-18eab8550397f1f3d4b8b2c5257c88dae25d58ed.tar.bz2 | |
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 <venkatesh.pallipadi@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'drivers/acpi/processor_idle.c')
| -rw-r--r-- | drivers/acpi/processor_idle.c | 20 |
1 files changed, 15 insertions, 5 deletions
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 { /* |