On Thu, Feb 06, 2020 at 03:45:32PM +0100, Jean Delvare wrote:
> Hi Mika,
>
> On Wed, 5 Feb 2020 18:38:31 +0200, Mika Westerberg wrote:
> > On Wed, Feb 05, 2020 at 08:30:48AM -0800, Guenter Roeck wrote:
> > > On Wed, Feb 05, 2020 at 05:24:35PM +0200, Mika Westerberg wrote:
> > > > You should be able to revert to iTCO_wdt by simply disabling
> > > > CONFIG_WDAT_WDT from .config. Then acpi_has_watchdog() returns false
> > > > which means that iTCO_wdt is used instead.
> > >
> > > That may not be possible in a generic distribution.
> >
> > Right, they would need to build their own kernel. Currently there is no
> > way to do that without changing .config.
>
> OK, that's pretty much what I was compl^Wworried about ;-) Would you
> consider applying something like the following patch?
Yes, I think the patch makes sense.
Rafael, I guess you will take this since it is touching ACPI?
> From: Jean Delvare <jdelvare@xxxxxxx>
> Subject: ACPI / watchdog: Allow disabling WDAT at boot
>
> In case the WDAT interface is broken, give the user the option to
> ignore it to let a native driver bind to the watchdog device instead.
>
> Signed-off-by: Jean Delvare <jdelvare@xxxxxxx>
> Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
> Cc: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
Acked-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx>
> Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
> ---
> Documentation/admin-guide/kernel-parameters.txt | 4 ++++
> drivers/acpi/acpi_watchdog.c | 12 +++++++++++-
> 2 files changed, 15 insertions(+), 1 deletion(-)
>
> --- linux-5.4.orig/drivers/acpi/acpi_watchdog.c 2020-02-06 15:20:27.187333079 +0100
> +++ linux-5.4/drivers/acpi/acpi_watchdog.c 2020-02-06 15:30:08.707408406 +0100
> @@ -55,12 +55,14 @@ static bool acpi_watchdog_uses_rtc(const
> }
> #endif
>
> +static bool acpi_no_watchdog;
> +
> static const struct acpi_table_wdat *acpi_watchdog_get_wdat(void)
> {
> const struct acpi_table_wdat *wdat = NULL;
> acpi_status status;
>
> - if (acpi_disabled)
> + if (acpi_disabled || acpi_no_watchdog)
> return NULL;
>
> status = acpi_get_table(ACPI_SIG_WDAT, 0,
> @@ -88,6 +90,14 @@ bool acpi_has_watchdog(void)
> }
> EXPORT_SYMBOL_GPL(acpi_has_watchdog);
>
> +/* ACPI watchdog can be disabled on boot command line */
> +static int __init disable_acpi_watchdog(char *str)
> +{
> + acpi_no_watchdog = true;
> + return 1;
> +}
> +__setup("acpi_no_watchdog", disable_acpi_watchdog);
> +
> void __init acpi_watchdog_init(void)
> {
> const struct acpi_wdat_entry *entries;
> --- linux-5.4.orig/Documentation/admin-guide/kernel-parameters.txt 2020-02-06 15:20:27.187333079 +0100
> +++ linux-5.4/Documentation/admin-guide/kernel-parameters.txt 2020-02-06 15:31:16.614155680 +0100
> @@ -136,6 +136,10 @@
> dynamic table installation which will install SSDT
> tables to /sys/firmware/acpi/tables/dynamic.
>
> + acpi_no_watchdog [HW,ACPI,WDT]
> + Ignore the ACPI-based watchdog interface (WDAT) and let
> + a native driver control the watchdog device instead.
> +
> acpi_rsdp= [ACPI,EFI,KEXEC]
> Pass the RSDP address to the kernel, mostly used
> on machines running EFI runtime service to boot the
>
> Thanks,
> --
> Jean Delvare
> SUSE L3 Support
