From 9a4888888cc09b0ff3d0a1dd32df88742d29a293 Mon Sep 17 00:00:00 2001 From: Zhang Rui Date: Tue, 13 Oct 2020 15:35:57 +0800 Subject: ACPI: reboot: Avoid racing after writing to ACPI RESET_REG 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 Signed-off-by: Zhang Rui [ rjw: Edit comment in the code and subject ] Signed-off-by: Rafael J. Wysocki --- drivers/acpi/reboot.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'drivers/acpi/reboot.c') diff --git a/drivers/acpi/reboot.c b/drivers/acpi/reboot.c index ca707f5b521d..2a61f884e222 100644 --- a/drivers/acpi/reboot.c +++ b/drivers/acpi/reboot.c @@ -3,6 +3,7 @@ #include #include #include +#include #ifdef CONFIG_PCI static void acpi_pci_reboot(struct acpi_generic_address *rr, u8 reset_value) @@ -66,4 +67,14 @@ void acpi_reboot(void) acpi_reset(); break; } + + /* + * Some platforms do not shut down immediately after writing to the + * ACPI reset register, and this results in racing with the + * subsequent reboot mechanism. + * + * The 15ms delay has been found to be long enough for the system + * to reboot on the affected platforms. + */ + mdelay(15); } -- cgit v1.2.3