On Tue, Oct 13, 2020 at 9:36 AM Zhang Rui <rui.zhang@xxxxxxxxx> wrote: > > 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); > } > -- Applied as 5.10-rc material with some edits in the comment above and subject. Thanks!
