linux-kernel - Re: [PATCH v3] i8k: Autodetect maximal fan speed and fan RPM multiplier

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Date:	Sun, 21 Dec 2014 18:25:13 +0100
From:	Pali Rohár <pali.rohar@...il.com>
To:	Steven Honeyman <stevenhoneyman@...il.com>
Cc:	Guenter Roeck <linux@...ck-us.net>, Arnd Bergmann <arnd@...db.de>,
	"Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
	linux-kernel@...r.kernel.org,
	Valdis Kletnieks <Valdis.Kletnieks@...edu>,
	Jean Delvare <jdelvare@...e.de>,
	Gabriele Mazzotta <gabriele.mzt@...il.com>,
	Jochen Eisinger <jochen@...guin-breeder.org>
Subject: Re: [PATCH v3] i8k: Autodetect maximal fan speed and fan RPM multiplier

On Sunday 21 December 2014 17:55:51 Steven Honeyman wrote:
> On 21 December 2014 at 16:37, Pali Rohár <pali.rohar@...il.com> 
wrote:
> > On Sunday 21 December 2014 13:23:32 Guenter Roeck wrote:
> >> On 12/21/2014 04:09 AM, Pali Rohár wrote:
> >> > On Sunday 21 December 2014 12:57:08 Guenter Roeck wrote:
> >> >>> -#define I8K_FAN_MULT             30
> >> >>> +#define I8K_FAN_MAX_RPM          30000
> >> >>> 
> >> >>>    #define I8K_MAX_TEMP           127
> >> >>>    
> >> >>>    #define I8K_FN_NONE            0x00
> >> >>> 
> >> >>> @@ -64,7 +66,7 @@ static DEFINE_MUTEX(i8k_mutex);
> >> >>> 
> >> >>>    static char bios_version[4];
> >> >>>    static struct device *i8k_hwmon_dev;
> >> >>>    static u32 i8k_hwmon_flags;
> >> >>> 
> >> >>> -static int i8k_fan_mult;
> >> >>> +static int i8k_fan_mult = 30;
> >> >> 
> >> >> Why did you drop I8K_FAN_MULT ?
> >> > 
> >> > Because I think it is not needed anymore... It is used
> >> > only in one place (there ^). But if you want I can
> >> > revert it back.
> >> 
> >> That is not a reason to drop a define.
> >> 
> >> >>>    static int __init i8k_probe(void)
> >> >>>    {
> >> >>> 
> >> >>> + const struct i8k_config_data *conf;
> >> >> 
> >> >> Why did you move this variable declaration ?
> >> > 
> >> > Comes from previous version of patches where I moved all
> >> > variables to start of function. I will revert this
> >> > change.
> >> > 
> >> >>> -         const struct i8k_config_data *conf =
> >> >>> id->driver_data; +         conf = id->driver_data;
> >> >>> +         if (fan_mult <= 0 && conf->fan_mult > 0)
> >> >> 
> >> >> I still don't see the value in accepting fan_mult < 0
> >> >> (compeared to == 0).
> >> > 
> >> > Ok. What kernel driver should do if user load it with
> >> > negative parameter? We should not propagate negative
> >> > value to functions.
> >> 
> >> You have multiple options: Ignore it (bad idea ;-), abort
> >> loading the module with -EINVAL, or make the module
> >> parameter an unsigned.
> > 
> > And how to make module parameter as unsigned? It is
> > possible?
> > 
> > Code
> > 
> > module_param(fan_mult, unsigned int, 0);
> > 
> > cause compile error:
> > 
> > i8k.c:99:1: error: expected ‘=’, ‘,’, ‘;’, ‘asm’ or
> > ‘__attribute__’ before ‘int’ i8k.c:99:1: error:
> > ‘param_ops_unsigned’ undeclared here (not in a function)
> 
> module_param(fan_mult, uint, 0);
> 
> 
> Steven.

Thanks! I sent new patch which change module param to uint and 
after then I sent new version v4 of autodetect patch.

-- 
Pali Rohár
pali.rohar@...il.com

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