linux-kernel - Re: [PATCH 3/4] i2c: i801: Do not create iTCO watchdog when WDAT table exists

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Message-ID: <20160914200401.GB14003@roeck-us.net>
Date:   Wed, 14 Sep 2016 13:04:01 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Mika Westerberg <mika.westerberg@...ux.intel.com>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>, Jean Delvare <jdelvare@...e.com>,
        Wolfram Sang <wsa@...-dreams.de>,
        Peter Tyser <ptyser@...-inc.com>,
        Lee Jones <lee.jones@...aro.org>,
        Zha Qipeng <qipeng.zha@...el.com>,
        Darren Hart <dvhart@...radead.org>,
        Wim Van Sebroeck <wim@...ana.be>, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/4] i2c: i801: Do not create iTCO watchdog when WDAT
 table exists

On Tue, Sep 13, 2016 at 06:23:35PM +0300, Mika Westerberg wrote:
> ACPI WDAT table is the preferred way to use hardware watchdog over the
> native iTCO_wdt. Windows only uses this table for its hardware watchdog
> implementation so we should be relatively safe to trust it has been
> validated by OEMs
> 
> Prevent iTCO watchdog creation if we detect that there is ACPI WDAT table.
> 
> Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

> ---
>  drivers/i2c/busses/i2c-i801.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/i2c/busses/i2c-i801.c b/drivers/i2c/busses/i2c-i801.c
> index 5ef9b733d153..26298af73232 100644
> --- a/drivers/i2c/busses/i2c-i801.c
> +++ b/drivers/i2c/busses/i2c-i801.c
> @@ -1486,7 +1486,9 @@ static int i801_probe(struct pci_dev *dev, const struct pci_device_id *id)
>  		priv->features |= FEATURE_IRQ;
>  		priv->features |= FEATURE_SMBUS_PEC;
>  		priv->features |= FEATURE_BLOCK_BUFFER;
> -		priv->features |= FEATURE_TCO;
> +		/* If we have ACPI based watchdog use that instead */
> +		if (!acpi_has_watchdog())
> +			priv->features |= FEATURE_TCO;
>  		priv->features |= FEATURE_HOST_NOTIFY;
>  		break;
>  
> -- 
> 2.9.3
>