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| author | Zhang Rui <rui.zhang@intel.com> | 2020-10-13 15:35:57 +0800 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2020-10-16 18:04:52 +0200 |
| commit | 9a4888888cc09b0ff3d0a1dd32df88742d29a293 (patch) | |
| tree | 996376bd71c8900dd92afe2b656dae284ac609ee | |
| parent | cf1d2b44f6c701ffff58606b5b8a8996190d6e7d (diff) | |
| download | linux-9a4888888cc09b0ff3d0a1dd32df88742d29a293.tar.gz | |
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 <sukumar.ghorai@intel.com> Signed-off-by: Zhang Rui <rui.zhang@intel.com> [ rjw: Edit comment in the code and subject ] Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
| -rw-r--r-- | drivers/acpi/reboot.c | 11 |
1 files changed, 11 insertions, 0 deletions
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 <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 +67,14 @@ 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); } |