From: "Pali Rohár" <pali.rohar@gmail.com>
To: Gabriele Mazzotta <gabriele.mzt@gmail.com>
Cc: "Jean Delvare" <jdelvare@suse.com>,
"Guenter Roeck" <linux@roeck-us.net>,
"Michał Kępień" <kernel@kempniu.pl>,
"Andy Lutomirski" <luto@kernel.org>, Jethro <xtompok@gmail.com>,
linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [Experimental PATCH] dell-smm-hwmon: Add support for disabling automatic BIOS fan control
Date: Mon, 30 May 2016 11:32:04 +0200 [thread overview]
Message-ID: <20160530093204.GR29844@pali> (raw)
In-Reply-To: <830c86c9-af25-b31a-0526-4c1bc0232c53@gmail.com>
On Friday 27 May 2016 14:11:11 Gabriele Mazzotta wrote:
> On 22/05/2016 13:50, Pali Rohár wrote:
> > This patch exports standard hwmon pwmX_enable sysfs attribute for enabling
> > or disabling automatic fan control by BIOS. Standard value "1" is for
> > disabling automatic BIOS fan control and value "2" for enabling.
> >
> > Currently there is no way to check if BIOS auto mode is enabled (at least
> > it is not know how to do it), so hwmon sysfs attribute is write-only.
> >
> > By default BIOS auto mode is enabled by laptop firmware.
> >
> > When BIOS auto mode is enabled, custom fan speed value (set via hwmon pwmX
> > sysfs attribute) is overwritten by SMM in few seconds and therefore any
> > custom settings are without effect. So this is reason why implementing
> > option for disabling BIOS auto mode is needed.
> >
> > So finally this patch allows kernel to set and control fan speed on
> > laptops, but it can be dangerous (like setting speed of other fans).
> >
> > This new feature is highly experimental, uses Dell SMM calls, so does not
> > have to be supported by all laptops BIOSes. It was tested on Dell Latitude
> > E6440 with BIOS A5.
>
> Tested on a Dell XPS13 9333. Changing the value of pwm1_enable appears
> to have no effect here.
Can you check what i8k_enable_fan_auto_mode() returns? Error code or not?
--
Pali Rohár
pali.rohar@gmail.com
next prev parent reply other threads:[~2016-05-30 9:32 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-22 11:50 [Experimental PATCH] dell-smm-hwmon: Add support for disabling automatic BIOS fan control Pali Rohár
2016-05-22 15:04 ` Guenter Roeck
2016-05-22 15:17 ` Pali Rohár
2016-05-22 15:28 ` Guenter Roeck
2016-05-27 12:11 ` Gabriele Mazzotta
2016-05-30 9:32 ` Pali Rohár [this message]
2016-05-30 15:26 ` Gabriele Mazzotta
2016-06-02 13:09 ` Pali Rohár
2016-06-22 6:53 ` Michał Kępień
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