On 2017-05-31 09:51, jmondi wrote:
> Hi Peter,
>
> On Tue, May 30, 2017 at 01:04:08PM +0200, Peter Rosin wrote:
>> On 2017-05-30 10:54, Jacopo Mondi wrote:
>>> I2c-mux channels are created as mux siblings while they should be
>>> children of the mux itself. Fix it.
>>
>> Has this received any testing at all?
>>
>
> Yes, but on our specific use case, that apparently does not makes use of
> i2c_parent_is_i2c_adapter()
Try e.g. adding a client device with some address to the root i2c
adapter, and then add another client device with the same address
to one of the mux child adapters. Do that with and without your
patch. I suspect it will be allowed with your patch even though it
shouldn't.
>> I think it will break various users of i2c_parent_is_i2c_adapter()
>> that expect the current situation that a i2c mux child adapter is
>> direct child of the parent i2c adapter. I.e. with no intermediate
>> device node.
>
> Oh, I know see..
>
> So when walking the devices sitting on an i2c-adapter we should expect to
> see mux children adapters as well there. Do you think is there a way to
> easily identify them?
Well, you can use the method from i2c_parent_is_i2c_adapter() and
write a function like so (untested):
struct i2c_adapter *i2c_is_i2c_adapter(struct device *dev)
{
if (dev->type != &i2c_adapter_type)
return NULL;
return to_i2c_adapter(dev);
}
But why do you need to identify them? What problem are you trying to solve?
Also, I forgot to mention this in my first reply, but note that the
device implementing the i2c-mux need not be a child of the i2c adapter.
I.e. in your example, the device I'm talking about is gmsl-deserializer@0.
This "MUX" device could be e.g. a platform device situated in some other
completely random place in the device tree. Oh well, perhaps not random,
but I hope you get what I mean...
Cheers,
peda
> Thanks
> j
>>
>> Cheers,
>> peda
>>
>>> Signed-off-by: Jacopo Mondi <jacopo+renesas@xxxxxxxxxx>
>>> Suggested-by: Laurent Pinchart <laurent.pinchart@xxxxxxxxxxxxxxxx>
>>> ---
>>>
>>> Hello,
>>> while inspecting child nodes of an i2c adapter it has been noted that
>>> child devices of an i2c-mux are listed as children of the i2c adapter itself,
>>> and not of the i2c-mux.
>>>
>>> The hierarchy of devices looked like
>>>
>>> -- i2c-04
>>> --- eeprom@57
>>> --- video_receiver@70
>>> --- video_receiver@34
>>> --- gmsl-deserializer@0 <-- MUX
>>> --- gmsl-deserializer@0/i2c@0 <-- MUX CHANNEL
>>>
>>> It now looks like
>>>
>>> -- i2c-04
>>> --- eeprom@57
>>> --- video_receiver@70
>>> --- video_receiver@34
>>> --- gmsl-deserializer@0
>>> ---- gmsl-deserializer@0/i2c@0
>>>
>>> v1 -> v2:
>>> - change commit message as suggested by Geert
>>>
>>> drivers/i2c/i2c-mux.c | 2 +-
>>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/i2c/i2c-mux.c b/drivers/i2c/i2c-mux.c
>>> index 83768e8..37b7804 100644
>>> --- a/drivers/i2c/i2c-mux.c
>>> +++ b/drivers/i2c/i2c-mux.c
>>> @@ -324,7 +324,7 @@ int i2c_mux_add_adapter(struct i2c_mux_core *muxc,
>>> priv->adap.owner = THIS_MODULE;
>>> priv->adap.algo = &priv->algo;
>>> priv->adap.algo_data = priv;
>>> - priv->adap.dev.parent = &parent->dev;
>>> + priv->adap.dev.parent = muxc->dev;
>>> priv->adap.retries = parent->retries;
>>> priv->adap.timeout = parent->timeout;
>>> priv->adap.quirks = parent->quirks;
>>> --
>>> 2.7.4
>>>
>>
