Re: [Q] i2c_new_device vs i2c_del_driver

[Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>]

On Tue, 17 Mar 2009 18:50:50 +0100 (CET), Guennadi Liakhovetski wrote:
> On Tue, 17 Mar 2009, Jean Delvare wrote:
> 
> > Hi Guennadi,
> > 
> > On Tue, 17 Mar 2009 18:24:49 +0100 (CET), Guennadi Liakhovetski wrote:
> > > I have a question regarding dynimically created i2c devices. If I have a 
> > > card with an i2c device on it. Once I load a driver for that card, it uses 
> > > its knowledge of the hardware and registers a new i2c device using 
> > > i2c_new_device. Then at some point a driver for that i2c device is loaded, 
> > > it calls i2c_add_driver, then its probe() method is called with the 
> > > dynamically created device. So far so good. Now I unload the i2c driver, 
> > > it calls i2c_del_driver(), and then, IIUC, __detach_adapter will be called 
> > > for all devices attached to this driver,
> > 
> > Actually,  __detach_adapter will be called for all *adapters* on the
> > system. Then in turn __detach_adapter does a number of actions on
> > devices present on said adapters.
> > 
> > > including our device from above, 
> > 
> > No. Your driver is a new-style one (otherwise you couldn't use
> > i2c_new_device) which means that __detach_adapter returns relatively
> > quickly. The only part of __detach_adapter which is run is the one
> > which removes auto-instantiated devices. This isn't the case of your
> > device (you instantiated it explicitly) so __detach_adapter is a no-op
> > for you.
> 
> Aha, so, the driver->clients list will not contain my device, and it won't 
> get unregistered. Ic.

Correct. Maybe I should have found a better name, like
driver->detected_clients, to make it clearer. Want me to change it
know? It should be straightforward.

-- 
Jean Delvare