i2c adapter scan device issue

i2c adapter scan device issue

[Lanttor]

Hi,

I have a confused problem as follows:

I instantiate a i2c device with function i2c_register_board_info();
This function pre-declare the I2C devices which live on this bus and the
call of it
is before the real i2c bus driver loaded.

In i2c_register_board_info(),
__i2c_first_dynamic_bus_num = busnum +1;

My i2c bus driver use i2c_add_adapter() to register adapter, In
i2c_add_adapter(),
res = idr_get_new_above(&i2c_adapter_idr, adapter,
                                __i2c_first_dynamic_bus_num , &id);

adapter->nr = id;

That means if I pass busnum 0 to i2c_register_board_info(), but my i2c
adapter will get
busnum 1 and so it can't scan pre-declared i2c devices.
In fact, I only have one i2c adapter.

It seems I can't use i2c_add_adapter(), instead of using
i2c_add_numbered_adapter, right?

Best Regards,
Lanttor

Re: i2c adapter scan device issue

[Jean Delvare]

On Wed, 25 Nov 2009 12:18:05 +0800, Lanttor wrote:
> Hi,
> 
> I have a confused problem as follows:
> 
> I instantiate a i2c device with function i2c_register_board_info();
> This function pre-declare the I2C devices which live on this bus and the
> call of it
> is before the real i2c bus driver loaded.
> 
> In i2c_register_board_info(),
> __i2c_first_dynamic_bus_num = busnum +1;
> 
> My i2c bus driver use i2c_add_adapter() to register adapter, In
> i2c_add_adapter(),
> res = idr_get_new_above(&i2c_adapter_idr, adapter,
>                                 __i2c_first_dynamic_bus_num , &id);
> 
> adapter->nr = id;
> 
> That means if I pass busnum 0 to i2c_register_board_info(), but my i2c
> adapter will get
> busnum 1 and so it can't scan pre-declared i2c devices.
> In fact, I only have one i2c adapter.
> 
> It seems I can't use i2c_add_adapter(), instead of using
> i2c_add_numbered_adapter, right?

Yes, you are correct. You can't predefine I2C devices with
i2c_register_board_info() if you don't also set I2C adapter numbers
with i2c_add_numbered_adapter(). Trying would be equivalent to sending a
letter to someone when you know the city and street number but not the
street name: unlikely to succeed.

-- 
Jean Delvare

Re: i2c adapter scan device issue

[Lanttor]

>
> Yes, you are correct. You can't predefine I2C devices with
> i2c_register_board_info() if you don't also set I2C adapter numbers
> with i2c_add_numbered_adapter(). Trying would be equivalent to sending a
> letter to someone when you know the city and street number but not the
> street name: unlikely to succeed.
>   
Thanks Jean.

In fact my bus driver used i2c_add_adapter() not i2c_add_numbered_adapter().
Now I use i2c_add_numbered_adapter() to replace 2c_add_adapter() and set
the bus number first.

In one word, you mean that i2c_add_adapter() can not work normally if
useing i2c_register_board_info() to pre-declare the i2c device, right?
I really need track i2c-stack in detail.

Best Regards,
Lanttor




------------------------------------------------------------------------
*From:* Jean Delvare <khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org>
*Sent:* 11/25/2009 4:12:18 PM +0800
*To:* Lanttor <lanttor.guo-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
*CC:* linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
*Subject:* i2c adapter scan device issue

> On Wed, 25 Nov 2009 12:18:05 +0800, Lanttor wrote:
>   
>> Hi,
>>
>> I have a confused problem as follows:
>>
>> I instantiate a i2c device with function i2c_register_board_info();
>> This function pre-declare the I2C devices which live on this bus and the
>> call of it
>> is before the real i2c bus driver loaded.
>>
>> In i2c_register_board_info(),
>> __i2c_first_dynamic_bus_num = busnum +1;
>>
>> My i2c bus driver use i2c_add_adapter() to register adapter, In
>> i2c_add_adapter(),
>> res = idr_get_new_above(&i2c_adapter_idr, adapter,
>>                                 __i2c_first_dynamic_bus_num , &id);
>>
>> adapter->nr = id;
>>
>> That means if I pass busnum 0 to i2c_register_board_info(), but my i2c
>> adapter will get
>> busnum 1 and so it can't scan pre-declared i2c devices.
>> In fact, I only have one i2c adapter.
>>
>> It seems I can't use i2c_add_adapter(), instead of using
>> i2c_add_numbered_adapter, right?
>>     
>
> Yes, you are correct. You can't predefine I2C devices with
> i2c_register_board_info() if you don't also set I2C adapter numbers
> with i2c_add_numbered_adapter(). Trying would be equivalent to sending a
> letter to someone when you know the city and street number but not the
> street name: unlikely to succeed.
>
>   

Re: i2c adapter scan device issue

[Jean Delvare]

On Wed, 25 Nov 2009 16:42:02 +0800, Lanttor wrote:
> >
> > Yes, you are correct. You can't predefine I2C devices with
> > i2c_register_board_info() if you don't also set I2C adapter numbers
> > with i2c_add_numbered_adapter(). Trying would be equivalent to sending a
> > letter to someone when you know the city and street number but not the
> > street name: unlikely to succeed.
> >   
> Thanks Jean.
> 
> In fact my bus driver used i2c_add_adapter() not i2c_add_numbered_adapter().
> Now I use i2c_add_numbered_adapter() to replace 2c_add_adapter() and set
> the bus number first.
> 
> In one word, you mean that i2c_add_adapter() can not work normally if
> useing i2c_register_board_info() to pre-declare the i2c device, right?

Yes, exactly.

> I really need track i2c-stack in detail.

-- 
Jean Delvare
http://khali.linux-fr.org/wishlist.html