Re: [PATCH 0/4] i2c: Introduce i2c listeners

[David Brownell <david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>]

On Wednesday 04 June 2008, Trent Piepho wrote:
> Couldn't you say the probe function is called on a potential device?  The
> probe function can return -ENODEV, in which can other driver's probes get
> called, and it's perfectly ok if no driver binds to it.
> 
> The way PCI works, is that when a new pci bus is created, each address is
> probed

... by config space accessors which all PCI devices support.


> and a device is created if anything responds.  The generic bus code 
> tries to match each device to a driver or drivers

... using a formally managed set of product identifiers.


>	 and calls those drivers' 
> probe functions.  The drivers don't have to claim the device in the probe
> function.  The bus code handles all the cases of a driver or bus getting
> added or removed in various orders.
> 
> So why can't I2C do this too?

No such product identifiers, and in general no way to tell
what's sitting at a given address.  And in fact, there's no
sure way to tell if a device is present there, since when
an I2C device is busy, it's not required to ack its address.



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