ACPI Suspend: Enable ACPI during resume if SCI_EN is not set

From: Rafael J. Wysocki <[email protected]>

ACPI Suspend: Enable ACPI during resume if SCI_EN is not set

On some machines, like for example MSI Wind U100, the BIOS doesn't enable ACPI before returning control to the OS, which sometimes causes resume to fail. This is against the ACPI specification, which clearly states that "When the platform is waking from an S1, S2 or S3 state, OSPM assumes the hardware is already in the ACPI mode and will not issue an ACPI_ENABLE", but it won't hurt to check the SCI_EN bit and enable ACPI during resume from S3 if this bit is not set.

Fortunately, we already have acpi_enable() for that, so use it in the resume code path, before executing _BFS, in analogy with the resume-from-hibernation code path.

NOTE: We aren't supposed to set SCI_EN directly, because it's owned by the hardware.

Signed-off-by Rafael J. Wysocki <[email protected]>

---
 drivers/acpi/sleep/main.c |    2 ++
 1 file changed, 2 insertions(+)

Index: linux-2.6/drivers/acpi/sleep/main.c
===================================================================

drivers/acpi/sleep/main.c +2 -0

@@ -200,6 +200,8 @@ static int acpi_suspend_enter(suspend_st
 		break;
 	}
 
+	/* If ACPI is not enabled by the BIOS, we need to enable it here. */
+	acpi_enable();
 	/* Reprogram control registers and execute _BFS */
 	acpi_leave_sleep_state_prep(acpi_state);
 

applied to acpi-test.

Quoted 40 lines

From: Rafael J. Wysocki <[email protected]>

ACPI Suspend: Enable ACPI during resume if SCI_EN is not set

On some machines, like for example MSI Wind U100, the BIOS doesn't enable ACPI before returning control to the OS, which sometimes causes resume to fail. This is against the ACPI specification, which clearly states that "When the platform is waking from an S1, S2 or S3 state, OSPM assumes the hardware is already in the ACPI mode and will not issue an ACPI_ENABLE", but it won't hurt to check the SCI_EN bit and enable ACPI during resume from S3 if this bit is not set.

Fortunately, we already have acpi_enable() for that, so use it in the resume code path, before executing _BFS, in analogy with the resume-from-hibernation code path.

NOTE: We aren't supposed to set SCI_EN directly, because it's owned by the hardware.

Signed-off-by Rafael J. Wysocki <[email protected]>

---
 drivers/acpi/sleep/main.c |    2 ++
 1 file changed, 2 insertions(+)

Index: linux-2.6/drivers/acpi/sleep/main.c
===================================================================

drivers/acpi/sleep/main.c +2 -0

@@ -200,6 +200,8 @@ static int acpi_suspend_enter(suspend_st
 		break;
 	}
 
+	/* If ACPI is not enabled by the BIOS, we need to enable it here. */
+	acpi_enable();
 	/* Reprogram control registers and execute _BFS */
 	acpi_leave_sleep_state_prep(acpi_state);
 

applied to acpi-test.

Quoted 40 lines

From: Rafael J. Wysocki <[email protected]>

ACPI Suspend: Enable ACPI during resume if SCI_EN is not set

On some machines, like for example MSI Wind U100, the BIOS doesn't enable ACPI before returning control to the OS, which sometimes causes resume to fail. This is against the ACPI specification, which clearly states that "When the platform is waking from an S1, S2 or S3 state, OSPM assumes the hardware is already in the ACPI mode and will not issue an ACPI_ENABLE", but it won't hurt to check the SCI_EN bit and enable ACPI during resume from S3 if this bit is not set.

Fortunately, we already have acpi_enable() for that, so use it in the resume code path, before executing _BFS, in analogy with the resume-from-hibernation code path.

NOTE: We aren't supposed to set SCI_EN directly, because it's owned by the hardware.

Signed-off-by Rafael J. Wysocki <[email protected]>

---
 drivers/acpi/sleep/main.c |    2 ++
 1 file changed, 2 insertions(+)

Index: linux-2.6/drivers/acpi/sleep/main.c
===================================================================

drivers/acpi/sleep/main.c +2 -0

@@ -200,6 +200,8 @@ static int acpi_suspend_enter(suspend_st
 		break;
 	}
 
+	/* If ACPI is not enabled by the BIOS, we need to enable it here. */
+	acpi_enable();
 	/* Reprogram control registers and execute _BFS */
 	acpi_leave_sleep_state_prep(acpi_state);
 

From: Rafael J. Wysocki <[email protected]>

ACPI Suspend: Enable ACPI during resume if SCI_EN is not set

On some machines, like for example MSI Wind U100, the BIOS doesn't enable ACPI before returning control to the OS, which sometimes causes resume to fail. This is against the ACPI specification, which clearly states that "When the platform is waking from an S1, S2 or S3 state, OSPM assumes the hardware is already in the ACPI mode and will not issue an ACPI_ENABLE", but it won't hurt to check the SCI_EN bit and enable ACPI during resume from S3 if this bit is not set.

Fortunately, we already have acpi_enable() for that, so use it in the resume code path, before executing _BFS, in analogy with the resume-from-hibernation code path.

NOTE: We aren't supposed to set SCI_EN directly, because it's owned by the hardware.

Signed-off-by Rafael J. Wysocki <[email protected]>

From: Rafael J. Wysocki <[email protected]>

ACPI Suspend: Enable ACPI during resume if SCI_EN is not set

On some machines, like for example MSI Wind U100, the BIOS doesn't enable ACPI before returning control to the OS, which sometimes causes resume to fail. This is against the ACPI specification, which clearly states that "When the platform is waking from an S1, S2 or S3 state, OSPM assumes the hardware is already in the ACPI mode and will not issue an ACPI_ENABLE", but it won't hurt to check the SCI_EN bit and enable ACPI during resume from S3 if this bit is not set.

Fortunately, we already have acpi_enable() for that, so use it in the resume code path, before executing _BFS, in analogy with the resume-from-hibernation code path.

NOTE: We aren't supposed to set SCI_EN directly, because it's owned by the hardware.

Signed-off-by Rafael J. Wysocki <[email protected]>