From: Zhao Yakui <yakui.zhao@xxxxxxxxx> 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@xxxxxxxxx> Signed-off-by: Len Brown <len.brown@xxxxxxxxx> --- drivers/acpi/reboot.c | 25 ++++++++++++++++++++++--- 1 files changed, 22 insertions(+), 3 deletions(-) diff --git a/drivers/acpi/reboot.c b/drivers/acpi/reboot.c index a6b662c..755baf2 100644 --- 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; -- 1.5.5.1 -- 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
