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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>
This commit is contained in:
Zhang Rui 2020-10-13 15:35:57 +08:00 committed by Rafael J. Wysocki
parent cf1d2b44f6
commit 9a4888888c
1 changed files with 11 additions and 0 deletions
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11
drivers/acpi/reboot.c
View File

@ -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);
}