diff options
Diffstat (limited to 'drivers/acpi/reboot.c')
-rw-r--r-- | drivers/acpi/reboot.c | 25 |
1 files changed, 3 insertions, 22 deletions
diff --git a/drivers/acpi/reboot.c b/drivers/acpi/reboot.c index 755baf2ca70a..a6b662c00b67 100644 --- a/drivers/acpi/reboot.c +++ b/drivers/acpi/reboot.c | |||
@@ -15,28 +15,9 @@ void acpi_reboot(void) | |||
15 | 15 | ||
16 | rr = &acpi_gbl_FADT.reset_register; | 16 | rr = &acpi_gbl_FADT.reset_register; |
17 | 17 | ||
18 | /* | 18 | /* Is the reset register supported? */ |
19 | * Is the ACPI reset register supported? | 19 | if (!(acpi_gbl_FADT.flags & ACPI_FADT_RESET_REGISTER) || |
20 | * | 20 | rr->bit_width != 8 || rr->bit_offset != 0) |
21 | * According to ACPI 3.0, FADT.flags.RESET_REG_SUP indicates | ||
22 | * whether the ACPI reset mechanism is supported. | ||
23 | * | ||
24 | * However, some boxes have this bit clear, yet a valid | ||
25 | * ACPI_RESET_REG & RESET_VALUE, and ACPI reboot is the only | ||
26 | * mechanism that works for them after S3. | ||
27 | * | ||
28 | * This suggests that other operating systems may not be checking | ||
29 | * the RESET_REG_SUP bit, and are using other means to decide | ||
30 | * whether to use the ACPI reboot mechanism or not. | ||
31 | * | ||
32 | * So when acpi reboot is requested, | ||
33 | * only the reset_register is checked. If the following | ||
34 | * conditions are met, it indicates that the reset register is supported. | ||
35 | * a. reset_register is not zero | ||
36 | * b. the access width is eight | ||
37 | * c. the bit_offset is zero | ||
38 | */ | ||
39 | if (!(rr->address) || rr->bit_width != 8 || rr->bit_offset != 0) | ||
40 | return; | 21 | return; |
41 | 22 | ||
42 | reset_value = acpi_gbl_FADT.reset_value; | 23 | reset_value = acpi_gbl_FADT.reset_value; |