Messages in this thread | | | Date | Thu, 15 Sep 2005 15:55:23 -0500 | From | Dmitry Torokhov <> | Subject | Re: [patch 09/28] Input: convert net/bluetooth to dynamic input_dev allocation |
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On 9/15/05, Vojtech Pavlik <vojtech@suse.cz> wrote: > On Thu, Sep 15, 2005 at 02:22:34PM -0500, Dmitry Torokhov wrote: > > They are devices - class devices :). I have the following distinction > > in my head - "normal" devices (bus devices) are real hardware devices > > and their drivers need to do resource and/or power management. Class > > devices represent virtual devices - some kind of abstraction - that > > unify and combine "real" devices from several buses into one class. > > Yes. While input drivers do need to care about power management usually, > the input device abstraction itself doesn't have to, which makes it > indeed a special kind of a device. >
Right. They just signal to underlying hardware driver when they are in use (open), but the actual power management is left to the specific bus/driver, not input core.
> I was always wondering whether the distinction between bus/class was > needed, as the border isn't very clear. >
Classes combine devices which are logically the same, i.e. they perform similar functions. Buses combine devices that are perform different functions but have similar hardware interface. For example a network cards - it is a class. You can have network card sit on a PCI, USB, ISA buses but for the rest of the kernel they are accesses through netdev abstraction. At least this is my understanding of our device model ;)
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