According to the ACPI spec, "The system must reset immediately following the write to the ACPI RESET_REG register.", but there are cases that the system does not follow this and results in racing with the subsequetial reboot mechanism, which brings unexpected behavior. Fix this by adding a 15ms delay after writing to the ACPI RESET_REG. Reported-by: Ghorai, Sukumar <sukumar.ghorai@xxxxxxxxx> Signed-off-by: Zhang Rui <rui.zhang@xxxxxxxxx> --- drivers/acpi/reboot.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/acpi/reboot.c b/drivers/acpi/reboot.c index ca707f5b521d..0e357cb5612f 100644 --- a/drivers/acpi/reboot.c +++ b/drivers/acpi/reboot.c @@ -3,6 +3,7 @@ #include <linux/pci.h> #include <linux/acpi.h> #include <acpi/reboot.h> +#include <linux/delay.h> #ifdef CONFIG_PCI static void acpi_pci_reboot(struct acpi_generic_address *rr, u8 reset_value) @@ -66,4 +67,13 @@ void acpi_reboot(void) acpi_reset(); break; } + + /* + * Some platforms do not shutdown immediately after writing to the + * ACPI reset register, and this results in racing with the + * subsequetial reboot mechanism. + * Delay for 15ms has been proved to be long enough for the system + * to reboot, for these platforms. + */ + mdelay(15); } -- 2.17.1
