diff options
| -rw-r--r-- | drivers/acpi/acpica/aclocal.h | 11 |
1 files changed, 7 insertions, 4 deletions
diff --git a/drivers/acpi/acpica/aclocal.h b/drivers/acpi/acpica/aclocal.h index 882b4b55867..ee986edfa0d 100644 --- a/drivers/acpi/acpica/aclocal.h +++ b/drivers/acpi/acpica/aclocal.h @@ -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) |