Re: [PATCH] i2c-eg20t: use dynamically registered adapter number

[Wolfram Sang <wsa@the-dreams.de>]

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> If not, it may make sense to add a helper function exposing
> __i2c_first_dynamic_bus_num to drivers (something like
> i2c_is_dynamic_bus_num().) After all, i2c_add_numbered_adapter() mostly
> makes sense if static i2c device definitions exist. If not,
> i2c_add_adapter() is just as good. So something like:
> 
> 	if (i2c_is_dynamic_bus_num(i))
> 		ret = i2c_add_adapter(pch_adap);
> 	else {
> 		pch_adap->nr = i;
> 		ret = i2c_add_numbered_adapter(pch_adap);
> 	}
> 
> may make sense. Unless someone has a better idea.

PASEMI does:

        smbus->adapter.nr = PCI_FUNC(dev->devfn);

I am unsure if there is any guarantee in what order PCI_FUNCs are
probed, yet I have the feeling we could try a little harder to get the
numbered adapter. What about this (untested, just to get the idea)?

static inline int i2c_add_adapter_try_numbered(struct i2c_adapter *new_adap)
{
	int ret;
	struct i2c_adapter *old_adap = i2c_get_adapter(new_adap->nr);

	if (old_adap && new_adap->nr >= __i2c_first_dynamic_bus_num) {
		i2c_put_adapter(old_adap);
		dev_dbg(&new_adap->dev, "Static bus number occupied, trying dynamic number\n");
		ret = i2c_add_adapter(new_adap);
	} else {
		ret = i2c_add_numbered_adapter(new_adap);
	}

	return ret;
}

I used 'static inline' because I think the drivers needing this should
carry the extra weight. But no major objection to put sth like this also
into the core. The documentation for this function should carry a big
note that this is only a workaround and it should not be used directly.

Thoughts?

   Wolfram


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