Re: [lm-sensors] [Nouveau] hwmon API update

[Martin Peres <martin.peres@free.fr>]

Le 03/03/2011 16:22, Guenter Roeck a écrit :
> On Thu, Mar 03, 2011 at 04:36:09AM -0500, Dave Airlie wrote:
>> On Mon, Feb 14, 2011 at 8:08 AM, Jean Delvare<khali@linux-fr.org>  wrote:
>>> On Sun, 13 Feb 2011 09:16:40 -0800, Guenter Roeck wrote:
>>>> On Sun, Feb 13, 2011 at 07:18:44AM -0500, Martin Peres wrote:
>>>>> Hi,
>>>>>
>>>>> I am working on power management on the nouveau driver and I need a way
>>>>> to get data out of and send commands to the i2c drivers from the kernel
>>>>> space.
>> Martin,
>>
>> you probably should have cc'ed Matthew since it was his patch you based this on,
>> and I think he can provide a good explaination.
>>
>> to clarify some points,
>>
>> radeon does probably want something exactly like this, we just haven't gotten to
>> it completely yet, I'd rather not have two drivers in the kernel for
>> exact same hardware,
>> and I believe sharing the hwmon code to do what we want is a good plan since you
>> don't go around reinventing wheels, but if hwmon/i2c maintainers have
>> no interest
>> it leaves with little choice but to implement about 5-10 i2c drivers
>> again in drm codebase.
>>
>> Maybe hwmon/i2c maintainers could suggest a cleaner way to implement
>> what we want,
>> which I think I can summarize as
>>
>> a) access to monitored values in-kernel
>> b) no userspace access to the same values except via sanitised via the driver.
>>
> This is not a matter of "no interest". Interest is there, but if one demands
> too much one may get nothing.
>
> Request for b) so far was "no userspace access", period. This is unacceptable
> since providing userspace access to monitored values is the whole point of hwmon.
>
> I could imagine an API that covers both a) and b), as long as b) focuses
> on the "sanitize" aspect and doesn't try to limit userspace access to attributes.
>
> Guenter
b) was introduced by Dave, I never asked for it because I don't mind 
duplicating sensor data (one hwmon device named nouveau and one for the 
raw access to the i2c chip).
My only wish was to provide a simple way for users to read/change their 
fan speed and get the GPU temperature no matter if their card have an 
i2c controller or not.
I do agree that sanitizing could be of interest, I especially think 
about tweaking the temperature value with parameters stored inside the 
vbios.

I am fully open to suggestions as long as it involves sharing the code 
in one way or another.

Martin

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