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authorZhao Yakui <yakui.zhao@intel.com>2008-10-17 14:22:27 -0400
committerLen Brown <len.brown@intel.com>2008-10-18 01:01:12 -0400
commit8fd145917fb62368a9b80db59562c20576238f5a (patch)
tree42b81ee305b6f35e98aed2690f696b32cb5c864b /drivers
parent3fa8749e584b55f1180411ab1b51117190bac1e5 (diff)
ACPI: Ingore the RESET_REG_SUP bit when using ACPI reset mechanism
According to ACPI 3.0, FADT.flags.RESET_REG_SUP indicates whether the ACPI reboot mechanism is supported. However, some boxes have this bit clear, have a valid ACPI_RESET_REG & RESET_VALUE, and ACPI reboot is the only mechanism that works for them after S3. This suggests that other operating systems may not be checking the RESET_REG_SUP bit, and are using other means to decide whether to use the ACPI reboot mechanism or not. Here we stop checking RESET_REG_SUP. Instead, When acpi reboot is requested, only the reset_register is checked. If the following conditions are met, it indicates that the reset register is supported. a. reset_register is not zero b. the access width is eight c. the bit_offset is zero http://bugzilla.kernel.org/show_bug.cgi?id=7299 http://bugzilla.kernel.org/show_bug.cgi?id=1148 Signed-off-by: Zhao Yakui <yakui.zhao@intel.com> Signed-off-by: Len Brown <len.brown@intel.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/acpi/reboot.c25
1 files changed, 22 insertions, 3 deletions
diff --git a/drivers/acpi/reboot.c b/drivers/acpi/reboot.c
index a6b662c00b67..755baf2ca70a 100644
--- a/drivers/acpi/reboot.c
+++ b/drivers/acpi/reboot.c
@@ -15,9 +15,28 @@ void acpi_reboot(void)
15 15
16 rr = &acpi_gbl_FADT.reset_register; 16 rr = &acpi_gbl_FADT.reset_register;
17 17
18 /* Is the reset register supported? */ 18 /*
19 if (!(acpi_gbl_FADT.flags & ACPI_FADT_RESET_REGISTER) || 19 * Is the ACPI reset register supported?
20 rr->bit_width != 8 || rr->bit_offset != 0) 20 *
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)
21 return; 40 return;
22 41
23 reset_value = acpi_gbl_FADT.reset_value; 42 reset_value = acpi_gbl_FADT.reset_value;