From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Francis Moreau" Subject: Re: qestion about I2C_CLASS_HWMON flag Date: Fri, 5 Sep 2008 10:57:56 +0200 Message-ID: <38b2ab8a0809050157yfb21b08v23ae368d3337c1ca@mail.gmail.com> References: <38b2ab8a0809040043g7f944872l47f84c53bb213829@mail.gmail.com> <38b2ab8a0809040105j7ae3aca8xd334a4d203d9415b@mail.gmail.com> <20080904103707.557ac764@hyperion.delvare> <38b2ab8a0809040149u2bc0342h5c32b87f9277322f@mail.gmail.com> <20080904120855.7e7b9720@hyperion.delvare> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20080904120855.7e7b9720@hyperion.delvare> Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org To: Jean Delvare Cc: Linux Kernel Mailing List , i2c@lm-sensors.org List-Id: linux-i2c@vger.kernel.org Good morning Jean, On Thu, Sep 4, 2008 at 12:08 PM, Jean Delvare 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