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* [PATCH v3]x86: Bypass legacy PIC and PIT in ACPI hardware reduced mode
@ 2015-03-11  8:09 Li, Aubrey
  2015-03-16 12:06 ` [tip:x86/urgent] x86/platform, acpi: " tip-bot for Li, Aubrey
  0 siblings, 1 reply; 2+ messages in thread
From: Li, Aubrey @ 2015-03-11  8:09 UTC (permalink / raw)
  To: Ingo Molnar
  Cc: alan, Arjan van de Ven, Rafael J. Wysocki, Brown, Len,
	H. Peter Anvin, x86, LKML

On a platform in ACPI Hardware-reduced mode, the legacy PIC and PIT
may not be initialized even though they may be present in silicon.
Touching these legacy components causes unexpected results on the system.

On the Bay Trail-T(ASUS-T100) platform, touching these legacy components
blocks platform hardware low idle power state(S0ix) during system
suspend. So we should bypass them in ACPI hardware reduced mode.

Suggested-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Li Aubrey <aubrey.li@linux.intel.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Alan Cox <alan@linux.intel.com>
---
 arch/x86/kernel/acpi/boot.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index b9e30da..adb56cb 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -1343,6 +1343,26 @@ static int __init dmi_ignore_irq0_timer_override(const struct dmi_system_id *d)
 }
 
 /*
+ * ACPI offers an alternative platform interface model that removes
+ * ACPI hardware requirements for platforms that do not implement
+ * the PC Architecture.
+ *
+ * We initialize the Hardware-reduced ACPI model here
+ */
+static void __init acpi_reduced_hw_init(void)
+{
+	if (acpi_gbl_reduced_hardware) {
+		/*
+		 * Override x86_init functions and bypass legacy pic
+		 * in Hardware-reduced ACPI mode
+		 */
+		x86_init.timers.timer_init	= x86_init_noop;
+		x86_init.irqs.pre_vector_init	= x86_init_noop;
+		legacy_pic			= &null_legacy_pic;
+	}
+}
+
+/*
  * If your system is blacklisted here, but you find that acpi=force
  * works for you, please contact linux-acpi@vger.kernel.org
  */
@@ -1541,6 +1561,11 @@ int __init early_acpi_boot_init(void)
 	 */
 	early_acpi_process_madt();
 
+	/*
+	 * Hardware-reduced ACPI mode initialization
+	 */
+	acpi_reduced_hw_init();
+
 	return 0;
 }
 
-- 
1.9.1

^ permalink raw reply	[flat|nested] 2+ messages in thread

* [tip:x86/urgent] x86/platform, acpi: Bypass legacy PIC and PIT in ACPI hardware reduced mode
  2015-03-11  8:09 [PATCH v3]x86: Bypass legacy PIC and PIT in ACPI hardware reduced mode Li, Aubrey
@ 2015-03-16 12:06 ` tip-bot for Li, Aubrey
  0 siblings, 0 replies; 2+ messages in thread
From: tip-bot for Li, Aubrey @ 2015-03-16 12:06 UTC (permalink / raw)
  To: linux-tip-commits
  Cc: mingo, len.brown, linux-kernel, tglx, hpa, alan, arjan, rjw,
	aubrey.li, rafael.j.wysocki, hpa

Commit-ID:  7486341a98f26857f383aec88ffa10950087c3a1
Gitweb:     http://git.kernel.org/tip/7486341a98f26857f383aec88ffa10950087c3a1
Author:     Li, Aubrey <aubrey.li@linux.intel.com>
AuthorDate: Wed, 11 Mar 2015 16:09:00 +0800
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Thu, 12 Mar 2015 12:07:13 +0100

x86/platform, acpi: Bypass legacy PIC and PIT in ACPI hardware reduced mode

On a platform in ACPI Hardware-reduced mode, the legacy PIC and
PIT may not be initialized even though they may be present in
silicon. Touching these legacy components causes unexpected
results on the system.

On the Bay Trail-T(ASUS-T100) platform, touching these legacy
components blocks platform hardware low idle power state(S0ix)
during system suspend. So we should bypass them in ACPI hardware
reduced mode.

Suggested-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Li Aubrey <aubrey.li@linux.intel.com>
Cc: <alan@linux.intel.com>
Cc: Alan Cox <alan@linux.intel.com>
Cc: H. Peter Anvin <hpa@linux.intel.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: Rafael J. Wysocki <rjw@rjwysocki.net>
Link: http://lkml.kernel.org/r/54FFF81C.20703@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 arch/x86/kernel/acpi/boot.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/arch/x86/kernel/acpi/boot.c b/arch/x86/kernel/acpi/boot.c
index 3d525c6..803b684 100644
--- a/arch/x86/kernel/acpi/boot.c
+++ b/arch/x86/kernel/acpi/boot.c
@@ -1338,6 +1338,26 @@ static int __init dmi_ignore_irq0_timer_override(const struct dmi_system_id *d)
 }
 
 /*
+ * ACPI offers an alternative platform interface model that removes
+ * ACPI hardware requirements for platforms that do not implement
+ * the PC Architecture.
+ *
+ * We initialize the Hardware-reduced ACPI model here:
+ */
+static void __init acpi_reduced_hw_init(void)
+{
+	if (acpi_gbl_reduced_hardware) {
+		/*
+		 * Override x86_init functions and bypass legacy pic
+		 * in Hardware-reduced ACPI mode
+		 */
+		x86_init.timers.timer_init	= x86_init_noop;
+		x86_init.irqs.pre_vector_init	= x86_init_noop;
+		legacy_pic			= &null_legacy_pic;
+	}
+}
+
+/*
  * If your system is blacklisted here, but you find that acpi=force
  * works for you, please contact linux-acpi@vger.kernel.org
  */
@@ -1536,6 +1556,11 @@ int __init early_acpi_boot_init(void)
 	 */
 	early_acpi_process_madt();
 
+	/*
+	 * Hardware-reduced ACPI mode initialization:
+	 */
+	acpi_reduced_hw_init();
+
 	return 0;
 }
 

^ permalink raw reply	[flat|nested] 2+ messages in thread

end of thread, other threads:[~2015-03-16 12:06 UTC | newest]

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