From: Lin Ming <ming.m.lin@xxxxxxxxx> Affects PM1 Control register only. When reading the register, zero the write-only bits as per the ACPI spec. ACPICA BZ 443. Lin Ming. http://www.acpica.org/bugzilla/show_bug.cgi?id=443 Signed-off-by: Lin Ming <ming.m.lin@xxxxxxxxx> Signed-off-by: Bob Moore <robert.moore@xxxxxxxxx> Signed-off-by: Len Brown <len.brown@xxxxxxxxx> --- drivers/acpi/acpica/aclocal.h | 4 ++++ drivers/acpi/acpica/hwregs.c | 7 +++++++ 2 files changed, 11 insertions(+), 0 deletions(-) diff --git a/drivers/acpi/acpica/aclocal.h b/drivers/acpi/acpica/aclocal.h index 42ef0cb..772ee5c 100644 --- a/drivers/acpi/acpica/aclocal.h +++ b/drivers/acpi/acpica/aclocal.h @@ -781,6 +781,10 @@ struct acpi_bit_register_info { */ #define ACPI_PM1_STATUS_PRESERVED_BITS 0x0800 /* Bit 11 */ +/* Write-only bits must be zeroed by software */ + +#define ACPI_PM1_CONTROL_WRITEONLY_BITS 0x2004 /* Bits 13, 2 */ + /* For control registers, both ignored and reserved bits must be preserved */ #define ACPI_PM1_CONTROL_IGNORED_BITS 0x0201 /* Bits 9, 0(SCI_EN) */ diff --git a/drivers/acpi/acpica/hwregs.c b/drivers/acpi/acpica/hwregs.c index f8ee0a7..7b2fb60 100644 --- a/drivers/acpi/acpica/hwregs.c +++ b/drivers/acpi/acpica/hwregs.c @@ -207,6 +207,13 @@ acpi_hw_register_read(u32 register_id, u32 * return_value) xpm1a_control_block, &acpi_gbl_FADT. xpm1b_control_block); + + /* + * Zero the write-only bits. From the ACPI specification, "Hardware + * Write-Only Bits": "Upon reads to registers with write-only bits, + * software masks out all write-only bits." + */ + value &= ~ACPI_PM1_CONTROL_WRITEONLY_BITS; break; case ACPI_REGISTER_PM2_CONTROL: /* 8-bit access */ -- 1.6.0.6 -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
