* [PATCH] acpi: reboot: fix racing after writing to ACPI RESET_REG
@ 2020-10-10 2:26 Zhang Rui
2020-10-12 10:42 ` Rafael J. Wysocki
0 siblings, 1 reply; 3+ messages in thread
From: Zhang Rui @ 2020-10-10 2:26 UTC (permalink / raw)
To: linux-acpi, rjw; +Cc: sukumar.ghorai, rui.zhang
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>
---
drivers/acpi/reboot.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/drivers/acpi/reboot.c b/drivers/acpi/reboot.c
index ca707f5b521d..88e6b083d702 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 +67,10 @@ void acpi_reboot(void)
acpi_reset();
break;
}
+
+ /*
+ * delay for 15ms in case the system does not shutdown immediately after
+ * writing to the ACPI reset register
+ */
+ mdelay(15);
}
--
2.17.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] acpi: reboot: fix racing after writing to ACPI RESET_REG
2020-10-10 2:26 [PATCH] acpi: reboot: fix racing after writing to ACPI RESET_REG Zhang Rui
@ 2020-10-12 10:42 ` Rafael J. Wysocki
2020-10-13 8:19 ` Zhang Rui
0 siblings, 1 reply; 3+ messages in thread
From: Rafael J. Wysocki @ 2020-10-12 10:42 UTC (permalink / raw)
To: Zhang Rui; +Cc: ACPI Devel Maling List, Rafael J. Wysocki, sukumar.ghorai
On Sat, Oct 10, 2020 at 4:36 AM Zhang Rui <rui.zhang@intel.com> 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@intel.com>
> Signed-off-by: Zhang Rui <rui.zhang@intel.com>
> ---
> drivers/acpi/reboot.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/drivers/acpi/reboot.c b/drivers/acpi/reboot.c
> index ca707f5b521d..88e6b083d702 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 +67,10 @@ void acpi_reboot(void)
> acpi_reset();
> break;
> }
> +
> + /*
> + * delay for 15ms in case the system does not shutdown immediately after
> + * writing to the ACPI reset register
It would also be good to make a note of where the 15ms value comes from.
Even if it has been guessed, it will still be good to know that, say,
5 years from now.
> + */
> + mdelay(15);
> }
> --
> 2.17.1
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] acpi: reboot: fix racing after writing to ACPI RESET_REG
2020-10-12 10:42 ` Rafael J. Wysocki
@ 2020-10-13 8:19 ` Zhang Rui
0 siblings, 0 replies; 3+ messages in thread
From: Zhang Rui @ 2020-10-13 8:19 UTC (permalink / raw)
To: Rafael J. Wysocki
Cc: ACPI Devel Maling List, Rafael J. Wysocki, sukumar.ghorai
On Mon, 2020-10-12 at 12:42 +0200, Rafael J. Wysocki wrote:
> On Sat, Oct 10, 2020 at 4:36 AM Zhang Rui <rui.zhang@intel.com>
> 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@intel.com>
> > Signed-off-by: Zhang Rui <rui.zhang@intel.com>
> > ---
> > drivers/acpi/reboot.c | 7 +++++++
> > 1 file changed, 7 insertions(+)
> >
> > diff --git a/drivers/acpi/reboot.c b/drivers/acpi/reboot.c
> > index ca707f5b521d..88e6b083d702 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 +67,10 @@ void acpi_reboot(void)
> > acpi_reset();
> > break;
> > }
> > +
> > + /*
> > + * delay for 15ms in case the system does not shutdown
> > immediately after
> > + * writing to the ACPI reset register
>
> It would also be good to make a note of where the 15ms value comes
> from.
>
> Even if it has been guessed, it will still be good to know that, say,
> 5 years from now.
>
Agreed, patch V2 sent out.
-rui
> > + */
> > + mdelay(15);
> > }
> > --
> > 2.17.1
> >
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2020-10-13 8:19 UTC | newest]
Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-10-10 2:26 [PATCH] acpi: reboot: fix racing after writing to ACPI RESET_REG Zhang Rui
2020-10-12 10:42 ` Rafael J. Wysocki
2020-10-13 8:19 ` Zhang Rui
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).