Hi all,
Is there any documentation about the i2c multimedia channel? I'm also
interested in adding such a feature to my system in order to monitor my
ATI radeon's (3650HD) temperature/fan.
Regards,
Ilyes.
Hans de Goede wrote:
> Thomas wrote:
>> Hallo,
>>
>> I wonder how difficult it would be to incorporate temperature and
>> fanspeed of ATI graphics cards into lm-sensors.
>>
>> There is the aticonfig tool which provides the data (and more, like
>> clockspeeds, ...):
>> aticonfig --adapter=0 --od-gettemperature
>> aticonfig --pplib-cmd "get fanspeed 0"
>>
>> What would be the best way to do that?
>> I guess I could do if I knew where to start :)
>>
>
> aticonfig is part of the proprietary driver, so lets forget about that path,
> besides that we really want to do this as standard in kernel hwmon drivers so
> that existing lm_sensors aware tools will just pick this info up as one
> additional sensor in the system.
>
> I've actually been looking into this, and it should be quite doable. I've
> looked at how to do this for my radeon 9800pro, so your milage may very with
> other cards.
>
> For my 9800 pro there is a standard (and already supported) fintek i2c hwmon IC
> (I don't remember the exact model) on the card. The big problem was that its on
> the radeon multimedia i2c channel, for which no in kernel i2c master ("adapter"
> in kernel / lm_sensor speak) driver exists, now this is fixable by just writing
> such a driver, but the problem is that the X server in some special cases (ATI
> all in wonder hardware) actually uses this i2c channel and thus pokes the
> register of the multimedia i2c controller off the radeon from userspace.
>
> But in comes modesetting, and it comes to the rescue in this case, as
> modesetting completely removes the need and ability for userspace to directly
> poke radeon registers. This has broken all in wonder support, but I'm sure this
> will get fixed eventually and that is a price we will have to pay for progress.
>
> In the hwmon case this is actually really good as now the way is free to add
> multimedia i2c support to the drm driver (and this is something which will be
> needed to fix the all in wonder cards) and once the i2c multimedia channel is
> supported as a normal kernel i2c adapter, lm_sensors should just work, atleast
> for my 9800.
>
> I've discussed this with Dave Airlie during the Linux Plumbers Conference, and
> he agreed that adding support for the multimedia i2c channel to the drm driver
> is the way forward. I've added him to the CC in case he has anything to add.
>
> If you want to look into adding support for hwmon to ati cards, writing
> multimedia i2c channel drm driver code would be the first step. I believe Dave
> Airlied is the person to talk to if you want to do that. I will gladly
> volunteer as a tester for this. (radeon 9800, radeon x1950 pro)
>
> Regards,
>
> Hans
>
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