From: Ian Pilcher <arequipeno@gmail.com>
To: lm-sensors@vger.kernel.org
Subject: Re: [lm-sensors] it87.fix_pwm_polarity
Date: Fri, 16 Aug 2013 19:28:14 +0000 [thread overview]
Message-ID: <520E7D4E.5030003@gmail.com> (raw)
In-Reply-To: <kuasuu$1j8$1@ger.gmane.org>
On 08/16/2013 01:57 PM, Guenter Roeck wrote:
> It just changes the pwm polarity from active low to active high unless
> fan control is set to automatic mode. That doesn't damage anything.
Good to know.
> Does automatic fan control for the drive bay fan work if you don't load
> the driver ? Also, what kernel log message do you get when you load the
> driver with or without the parameter ?
I don't believe so. Without the module loaded the fan seems to always
run at about 75% of its maximum speed.
It is hard to be 100% sure, because the temperatures reported by the
IT8728F don't seem to ever vary by more than a few degrees, even when
coretemp reports significant changes (around 20 degrees). So it's
possible that automatic fan control is "working," but getting garbage
input.
If I load the module after a cold-boot without the parameter, I get:
it87 it87.656: Detected broken BIOS defaults, disabling PWM interface
Once I've loaded it with the fix_pwm_polarity=1 one time, I can unload/
reload the module without any special parameters, and PWM continues to
work. IIRC, this is true across warm reboots.
Note that bad/incomplete setup by the BIOS appears to be somewhat common
on this hardware. This is a Thecus N5550 NAS, and the manufacturer
expects people to run their Linux-based "firmware." Their add-on kernel
modules do some setup work (configuring ICH GPIOs) which would normally
be done by the BIOS.
HTH
--
====================================
Ian Pilcher arequipeno@gmail.com
Sometimes there's nothing left to do but crash and burn...or die trying.
====================================
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next prev parent reply other threads:[~2013-08-16 19:28 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-12 14:54 [lm-sensors] it87.fix_pwm_polarity Ian Pilcher
2013-08-16 16:34 ` Ian Pilcher
2013-08-16 18:57 ` Guenter Roeck
2013-08-16 19:28 ` Ian Pilcher [this message]
2013-08-16 19:57 ` Guenter Roeck
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