linux-kernel - Re: Missing watchdog after ACPI watchdog creation failure

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Message-ID: <20180110152343.GO27654@lahna.fi.intel.com>
Date:   Wed, 10 Jan 2018 17:23:43 +0200
From:   Mika Westerberg <mika.westerberg@...ux.intel.com>
To:     Takashi Iwai <tiwai@...e.de>
Cc:     "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        linux-kernel@...r.kernel.org
Subject: Re: Missing watchdog after ACPI watchdog creation failure

On Wed, Jan 10, 2018 at 04:13:51PM +0100, Takashi Iwai wrote:
> Hi,
> 
> on the recent kernels, i2c-i801 skips the creation of iTCO wdt when
> ACPI WDAT is present.  It's fine when ACPI really creates the watchdog
> device.  But, we've got a report showing that the watchdog is missing
> on some machines because ACPI failed to create, and yet i2c-i801 still
> skips because acpi_has_watchdog() returns true.
> 
> More specifically, the machine gets an error from acpi_watchdog.c
> like:
>   platform wdat_wdt: failed to claim resource 3: [io 0x040a-0x040c]
>   ACPI: watchdog: Device creation failed: -16
> 
> where the region was registered by pnp,
>   % cat /proc/ioports
>   ....
>   0400-047f : pnp 00:01
> 
> 
> One may say that BIOS sucks, but OTOH, the complete lack of watchdog
> thereafter can be seen as a regression, too.  It used to work on the
> older kernel as iTCO wdt was provided by i2c-i801.

Hmm, if the resource is already taken I wonder how iTCO can work? Are
you sure iTCO works on those systems?

> Shouldn't acpi_has_watchdog() rather checks whether the watchdog
> device creation succeeded or not?

Yes, or rather we should first figure out what the actual problem is ;-)

Are you able to get acpidump from that system with full dmesg?