diff options
Diffstat (limited to 'drivers/acpi/acpica/hwregs.c')
| -rw-r--r-- | drivers/acpi/acpica/hwregs.c | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/drivers/acpi/acpica/hwregs.c b/drivers/acpi/acpica/hwregs.c index f8ee0a7fd44d..7b2fb602b5cb 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 */ |