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ACPICA: Disable preservation of SCI enable bit (SCI_EN) 

Preserving this bit breaks some machines. Not preserving this bit
seems to work OK in all cases, even though this goes against the
ACPI spec.

http://bugzilla.kernel.org/show_bug.cgi?id=13289

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
This commit is contained in:
Bob Moore 2009-05-21 11:05:03 +08:00 committed by Len Brown
parent 3362a6badb
commit b1cd843be7
1 changed files with 7 additions and 4 deletions
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11
drivers/acpi/acpica/aclocal.h
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@ -789,11 +789,14 @@ struct acpi_bit_register_info {
/* For control registers, both ignored and reserved bits must be preserved */
/*
* The ACPI spec says to ignore PM1_CTL.SCI_EN (bit 0)
* but we need to be able to write ACPI_BITREG_SCI_ENABLE directly
* as a BIOS workaround on some machines.
* For PM1 control, the SCI enable bit (bit 0, SCI_EN) is defined by the
* ACPI specification to be a "preserved" bit - "OSPM always preserves this
* bit position", section 4.7.3.2.1. However, on some machines the OS must
* write a one to this bit after resume for the machine to work properly.
* To enable this, we no longer attempt to preserve this bit. No machines
* are known to fail if the bit is not preserved. (May 2009)
*/
#define ACPI_PM1_CONTROL_IGNORED_BITS 0x0200 /* Bits 9 */
#define ACPI_PM1_CONTROL_IGNORED_BITS 0x0200 /* Bit 9 */
#define ACPI_PM1_CONTROL_RESERVED_BITS 0xC1F8 /* Bits 14-15, 3-8 */
#define ACPI_PM1_CONTROL_PRESERVED_BITS \
(ACPI_PM1_CONTROL_IGNORED_BITS | ACPI_PM1_CONTROL_RESERVED_BITS)