Messages in this thread | | | Date | Fri, 5 Sep 2008 10:57:56 +0200 | From | "Francis Moreau" <> | Subject | Re: qestion about I2C_CLASS_HWMON flag |
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Good morning Jean,
On Thu, Sep 4, 2008 at 12:08 PM, Jean Delvare <khali@linux-fr.org> wrote: > In general they can, yes (where they can't, it's due to restrictions in > protocol implementations, not device types.) But this isn't a matter of > what devices can be on the bus. This is a matter of what devices can be > probed for on a given bus. For example, hardware monitoring drivers > which handle I2C devices, make sure that I2C_CLASS_HWMON is set before > probing I2C addresses on a given bus in search of a device to > auto-detect. On the other hand, if they are merely attaching to an I2C > device which has already been instantiated (and thus no probing is > needed) they do not care about the class. The reason for this mechanism > is that probing can be risky, so we want to limit it to what is > strictly needed. For example, there is no point in probing the I2C bus > of a TV adapter for hardware monitoring chips - there simply can't be > any there. If there ever was any, that would be such a special case > that we would instantiate the I2C device in question explicitly from > the adapter code, so we have no need for probing.
OK but which devices that can be connected to an I2C bus is platform specific, isn't it ? For example, an I2C adapter can be used in a TV and in that case there may be no point to probe for a HW mon chips but this same I2C adapter can be used by other platforms in a different context where there's a HW mon chip.
So the flags probably are useful, but they're are hard coded in adapters...
Sorry if I'm still missing something. -- Francis
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