| From cebbert@redhat.com Tue Nov 4 15:02:34 2008 |
| From: Zhao Yakui <yakui.zhao@intel.com> |
| Date: Fri, 31 Oct 2008 17:25:45 -0400 |
| Subject: ACPI: Ingore the RESET_REG_SUP bit when using ACPI reset mechanism |
| To: stable@kernel.org |
| Cc: Len Brown <len.brown@intel.com> |
| Message-ID: <20081031172545.0a1486d9@redhat.com> |
| |
| From: Zhao Yakui <yakui.zhao@intel.com> |
| |
| Subject: ACPI: Ingore the RESET_REG_SUP bit when using ACPI reset mechanism |
| |
| commit 8fd145917fb62368a9b80db59562c20576238f5a upstream |
| |
| 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> |
| Cc: Chuck Ebbert <cebbert@redhat.com> |
| Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de> |
| |
| --- |
| drivers/acpi/reboot.c | 25 ++++++++++++++++++++++--- |
| 1 file changed, 22 insertions(+), 3 deletions(-) |
| |
| --- a/drivers/acpi/reboot.c |
| +++ b/drivers/acpi/reboot.c |
| @@ -15,9 +15,28 @@ void acpi_reboot(void) |
| |
| rr = &acpi_gbl_FADT.reset_register; |
| |
| - /* Is the reset register supported? */ |
| - if (!(acpi_gbl_FADT.flags & ACPI_FADT_RESET_REGISTER) || |
| - rr->bit_width != 8 || rr->bit_offset != 0) |
| + /* |
| + * Is the ACPI reset register supported? |
| + * |
| + * According to ACPI 3.0, FADT.flags.RESET_REG_SUP indicates |
| + * whether the ACPI reset mechanism is supported. |
| + * |
| + * However, some boxes have this bit clear, yet 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. |
| + * |
| + * So 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 |
| + */ |
| + if (!(rr->address) || rr->bit_width != 8 || rr->bit_offset != 0) |
| return; |
| |
| reset_value = acpi_gbl_FADT.reset_value; |