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authorLen Brown <len.brown@intel.com>2009-01-28 18:28:09 -0500
committerLen Brown <len.brown@intel.com>2009-01-28 19:15:54 -0500
commit31878dd86b7df9a147f5e6cc6e07092b4308782b (patch)
treee99eaf24e4d813bf43737f02c8746c17383a841d /drivers/acpi
parenta2b7b01c072435b7832ab392167545a1b38cabc3 (diff)
ACPI: remove BM_RLD access from idle entry path
It is true that BM_RLD needs to be set to enable bus master activity to wake an older chipset (eg PIIX4) from C3. This is contrary to the erroneous wording the ACPI 2.0, 3.0 specifications that suggests that BM_RLD is an indicator rather than a control bit. ACPI 1.0's correct wording should be restored in ACPI 4.0: http://www.acpica.org/bugzilla/show_bug.cgi?id=689 But the kernel should not have to clear BM_RLD when entering a non C3-type state just to set it again when entering a C3-type C-state. We should be able to set BM_RLD at boot time and leave it alone -- removing the overhead of accessing this IO register from the idle entry path. Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'drivers/acpi')
-rw-r--r--drivers/acpi/processor_idle.c57
1 files changed, 9 insertions, 48 deletions
diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
index ae0010821ce3..7eab733ae96e 100644
--- a/drivers/acpi/processor_idle.c
+++ b/drivers/acpi/processor_idle.c
@@ -241,26 +241,6 @@ acpi_processor_power_activate(struct acpi_processor *pr,
241 old->promotion.count = 0; 241 old->promotion.count = 0;
242 new->demotion.count = 0; 242 new->demotion.count = 0;
243 243
244 /* Cleanup from old state. */
245 if (old) {
246 switch (old->type) {
247 case ACPI_STATE_C3:
248 /* Disable bus master reload */
249 if (new->type != ACPI_STATE_C3 && pr->flags.bm_check)
250 acpi_set_register(ACPI_BITREG_BUS_MASTER_RLD, 0);
251 break;
252 }
253 }
254
255 /* Prepare to use new state. */
256 switch (new->type) {
257 case ACPI_STATE_C3:
258 /* Enable bus master reload */
259 if (old->type != ACPI_STATE_C3 && pr->flags.bm_check)
260 acpi_set_register(ACPI_BITREG_BUS_MASTER_RLD, 1);
261 break;
262 }
263
264 pr->power.state = new; 244 pr->power.state = new;
265 245
266 return; 246 return;
@@ -1121,7 +1101,6 @@ static void acpi_processor_power_verify_c3(struct acpi_processor *pr,
1121 " for C3 to be enabled on SMP systems\n")); 1101 " for C3 to be enabled on SMP systems\n"));
1122 return; 1102 return;
1123 } 1103 }
1124 acpi_set_register(ACPI_BITREG_BUS_MASTER_RLD, 0);
1125 } 1104 }
1126 1105
1127 /* 1106 /*
@@ -1137,6 +1116,15 @@ static void acpi_processor_power_verify_c3(struct acpi_processor *pr,
1137#else 1116#else
1138 cx->latency_ticks = cx->latency; 1117 cx->latency_ticks = cx->latency;
1139#endif 1118#endif
1119 /*
1120 * On older chipsets, BM_RLD needs to be set
1121 * in order for Bus Master activity to wake the
1122 * system from C3. Newer chipsets handle DMA
1123 * during C3 automatically and BM_RLD is a NOP.
1124 * In either case, the proper way to
1125 * handle BM_RLD is to set it and leave it set.
1126 */
1127 acpi_set_register(ACPI_BITREG_BUS_MASTER_RLD, 1);
1140 1128
1141 return; 1129 return;
1142} 1130}
@@ -1400,25 +1388,6 @@ static int acpi_idle_bm_check(void)
1400} 1388}
1401 1389
1402/** 1390/**
1403 * acpi_idle_update_bm_rld - updates the BM_RLD bit depending on target state
1404 * @pr: the processor
1405 * @target: the new target state
1406 */
1407static inline void acpi_idle_update_bm_rld(struct acpi_processor *pr,
1408 struct acpi_processor_cx *target)
1409{
1410 if (pr->flags.bm_rld_set && target->type != ACPI_STATE_C3) {
1411 acpi_set_register(ACPI_BITREG_BUS_MASTER_RLD, 0);
1412 pr->flags.bm_rld_set = 0;
1413 }
1414
1415 if (!pr->flags.bm_rld_set && target->type == ACPI_STATE_C3) {
1416 acpi_set_register(ACPI_BITREG_BUS_MASTER_RLD, 1);
1417 pr->flags.bm_rld_set = 1;
1418 }
1419}
1420
1421/**
1422 * acpi_idle_do_entry - a helper function that does C2 and C3 type entry 1391 * acpi_idle_do_entry - a helper function that does C2 and C3 type entry
1423 * @cx: cstate data 1392 * @cx: cstate data
1424 * 1393 *
@@ -1473,9 +1442,6 @@ static int acpi_idle_enter_c1(struct cpuidle_device *dev,
1473 return 0; 1442 return 0;
1474 } 1443 }
1475 1444
1476 if (pr->flags.bm_check)
1477 acpi_idle_update_bm_rld(pr, cx);
1478
1479 t1 = inl(acpi_gbl_FADT.xpm_timer_block.address); 1445 t1 = inl(acpi_gbl_FADT.xpm_timer_block.address);
1480 acpi_idle_do_entry(cx); 1446 acpi_idle_do_entry(cx);
1481 t2 = inl(acpi_gbl_FADT.xpm_timer_block.address); 1447 t2 = inl(acpi_gbl_FADT.xpm_timer_block.address);
@@ -1527,9 +1493,6 @@ static int acpi_idle_enter_simple(struct cpuidle_device *dev,
1527 */ 1493 */
1528 acpi_state_timer_broadcast(pr, cx, 1); 1494 acpi_state_timer_broadcast(pr, cx, 1);
1529 1495
1530 if (pr->flags.bm_check)
1531 acpi_idle_update_bm_rld(pr, cx);
1532
1533 if (cx->type == ACPI_STATE_C3) 1496 if (cx->type == ACPI_STATE_C3)
1534 ACPI_FLUSH_CPU_CACHE(); 1497 ACPI_FLUSH_CPU_CACHE();
1535 1498
@@ -1621,8 +1584,6 @@ static int acpi_idle_enter_bm(struct cpuidle_device *dev,
1621 */ 1584 */
1622 acpi_state_timer_broadcast(pr, cx, 1); 1585 acpi_state_timer_broadcast(pr, cx, 1);
1623 1586
1624 acpi_idle_update_bm_rld(pr, cx);
1625
1626 /* 1587 /*
1627 * disable bus master 1588 * disable bus master
1628 * bm_check implies we need ARB_DIS 1589 * bm_check implies we need ARB_DIS