From: "Pali Rohár" <pali.rohar@gmail.com>
To: Guenter Roeck <linux@roeck-us.net>
Cc: Arnd Bergmann <arnd@arndb.de>,
"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
Steven Honeyman <stevenhoneyman@gmail.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] i8k: Fix temperature bug handling in i8k_get_temp()
Date: Sun, 30 Nov 2014 15:48:15 +0100 [thread overview]
Message-ID: <201411301548.16031@pali> (raw)
In-Reply-To: <547ADC90.8000507@roeck-us.net>
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On Sunday 30 November 2014 10:00:00 Guenter Roeck wrote:
> On 11/18/2014 06:56 AM, Pali Rohár wrote:
> > Static array prev[] was incorrectly initialized. It should
> > be initialized to some "invalid" temperature value (above
> > I8K_MAX_TEMP).
> >
> > Next, function should store "invalid" value to prev[] (above
> > I8K_MAX_TEMP), not valid (= I8K_MAX_TEMP) because whole
> > temperature bug handling will not work.
> >
> > And last part, to not break existing detection of
> > temperature sensors, register them also if i8k report too
> > high temperature (above I8K_MAX_TEMP). This is needed
> > because some sensors are sometimes turned off (e.g sensor
> > on GPU which can be turned off/on) and in this case SMM
> > report too high value.
> >
> > To prevent reporting "invalid" values to userspace, return
> > -EINVAL. In this case sensors which are currently turned
> > off (e.g optimus/powerexpress/enduro gpu) are reported as
> > "N/A" by lm-sensors package.
> >
> > Signed-off-by: Pali Rohár <pali.rohar@gmail.com>
> > ---
> >
> > drivers/char/i8k.c | 16 ++++++++++------
> > 1 file changed, 10 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/char/i8k.c b/drivers/char/i8k.c
> > index 7272b08..e34a019 100644
> > --- a/drivers/char/i8k.c
> > +++ b/drivers/char/i8k.c
> > @@ -298,7 +298,7 @@ static int i8k_get_temp(int sensor)
> >
> > int temp;
> >
> > #ifdef I8K_TEMPERATURE_BUG
> >
> > - static int prev[4];
> > + static int prev[4] = { I8K_MAX_TEMP+1, I8K_MAX_TEMP+1,
> > I8K_MAX_TEMP+1, I8K_MAX_TEMP+1 };
> >
> > #endif
> >
> > regs.ebx = sensor & 0xff;
> > rc = i8k_smm(®s);
> >
> > @@ -317,10 +317,12 @@ static int i8k_get_temp(int sensor)
> >
> > */
> >
> > if (temp > I8K_MAX_TEMP) {
> >
> > temp = prev[sensor];
> >
> > - prev[sensor] = I8K_MAX_TEMP;
> > + prev[sensor] = I8K_MAX_TEMP+1;
> >
> > } else {
> >
> > prev[sensor] = temp;
> >
> > }
> >
> > + if (temp > I8K_MAX_TEMP)
> > + return -ERANGE;
>
> Can we return -ENODATA in this case ? I think that would be
> more appropriate.
>
This is internal kernel function, no problem. If you prefer
NODATA instead RANGE I will change it.
> > #endif
> >
> > return temp;
> >
> > @@ -499,6 +501,8 @@ static ssize_t
> > i8k_hwmon_show_temp(struct device *dev,
> >
> > int temp;
> >
> > temp = i8k_get_temp(index);
> >
> > + if (temp == -ERANGE)
> > + return -EINVAL;
>
> and can we also return -ENODATA to user space ?
> This would make the code a bit cleaner.
>
> Thanks,
> Guenter
There was some problems when I tested similar patch for radeon.ko
(do not report temperature to userspace when card is turned off).
I can test lm-sensors which is in Ubuntu 12.04 LTS (there is
probably some older version) what happens with -ENODATA from i8k.
--
Pali Rohár
pali.rohar@gmail.com
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next prev parent reply other threads:[~2014-11-30 14:48 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-19 14:46 [PATCH] i8k: Ignore temperature sensors which report invalid values Pali Rohár
2014-10-19 15:13 ` Guenter Roeck
2014-10-20 16:46 ` Pali Rohár
2014-10-21 4:27 ` Guenter Roeck
2014-10-22 12:29 ` Pali Rohár
2014-10-22 16:19 ` Guenter Roeck
2014-10-22 16:35 ` Pali Rohár
2014-10-22 17:10 ` Guenter Roeck
2014-10-23 10:37 ` Pali Rohár
2014-10-23 16:45 ` Guenter Roeck
2014-11-17 8:35 ` Pali Rohár
2014-11-18 5:56 ` Guenter Roeck
2014-11-18 14:46 ` Pali Rohár
2014-11-18 14:56 ` [PATCH] i8k: Fix temperature bug handling in i8k_get_temp() Pali Rohár
2014-11-30 0:12 ` Guenter Roeck
2014-11-30 14:44 ` Pali Rohár
2014-11-30 9:00 ` Guenter Roeck
2014-11-30 14:48 ` Pali Rohár [this message]
2014-11-30 15:56 ` Guenter Roeck
2014-11-30 16:00 ` Pali Rohár
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