RE: Need help on selecting one (and only one) i2c bus

[Ayman KHAMOUMA <ayman.khamouma-qxv4g6HH51o@public.gmane.org>]

Thanks a lot Jean,

Well I added bus 1 and 2 to the ignore list because I thought it wat a clean
way to do it.
There is nothing at 0x71 of bus 1 and 2.
I just wanted my code to be a "generic" code and to work even if in the
future some devices were added in bus 1 et 2.

Thanks again for your help,

Ayman KHAMOUMA

-----Original Message-----
From: Jean Delvare [mailto:khali-PUYAD+kWke1g9hUCZPvPmw@public.gmane.org] 
Sent: Wednesday, March 11, 2009 12:23 PM
To: Ayman KHAMOUMA
Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: Need help on selecting one (and only one) i2c bus

Hi Ayman,

On Wed, 11 Mar 2009 11:55:22 +0100, Ayman KHAMOUMA wrote:
> After some researches I guess I have to use the normal_i2c and ignore
> arrays:
> 
> static unsigned short normal_i2c[] = { 0x71, I2C_CLIENT_END}; static 
> unsigned short ignore[] = { 0x01, 0x71, 0x02, 0x71, I2C_CLIENT_END};
> 
> static struct i2c_client_address_data addr_data = {
>     .normal_i2c = normal_i2c,
>     .ignore     = ignore,
> };
> 
> Int the init function I have to allocate a major to the driver, and 
> than add the I2c driver:
> i2c_add_driver(&i2c_my_drv);
> 
> After doing that, i2c_my_drv.attach_adapter is called.
> 
> Which will call (among others) my probe function, in which I call 
> i2c_attach_client.
> 
> 
> Am I in the right way ?

No. You're using the old, deprecated way to instantiate devices, and you are
abusing it (the ignore array wasn't meant to be used the way you do.)

You said you're using kernel 2.6.23.17, it's not brand new, but it's not too
old either. At any rate, it already includes the new-style device binding.
So, instead of using the old binding model and then fight to get your driver
to _not_ attach to improper devices/addresses, you should use the new model
and explicitly instantiate your device, so that your driver won't even try
to bind to the wrong devices.

I have posted an explanation about how to do this recently:
http://marc.info/?l=linux-i2c&m=123659553713018&w=2

You should convert your driver to a new-style one and use either method
1 or method 2, whichever is easier for you. See the following document for a
guide on how to update your code:
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob_plai
n;f=Documentation/i2c/upgrading-clients;hb=HEAD

It's for kernel 2.6.26 and later but it should mostly apply to 2.6.23 too.
The only big difference I can think of is that 2.6.23 doesn't have struct
i2c_device_id, instead the device driver binding is based on the i2c driver
name. I can help you with this if you can't figure it out.

As a side note, the fact that you needed to add buses 1 and 2 to the ignore
list suggests that something is wrong with your I2C bus driver.
It is rather unlikely that all 3 I2C buses on your system have a device at
address 0x71, so your old-style driver shouldn't have instantiated 3
devices. If it did, it strongly suggests that the quick write i2c-core is
using to check for the presence of a device at a given address improperly
reported success in all cases. You really should check your I2C bus driver
and in particular the implementation of 0-byte messages before going further
with the device driver.

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