[U-Boot] [PATCH v3 3/9] dm: uclass: Add uclass_foreach_dev_probe

[Patrice CHOTARD]

Hi Bin

On 10/12/2018 12:13 PM, Bin Meng wrote:
> Hi Patrice,
> 
> On Fri, Oct 12, 2018 at 3:51 PM Patrice CHOTARD <patrice.chotard at st.com> wrote:
>>
>> Hi Bin
>>
>> On 10/11/2018 11:06 AM, Bin Meng wrote:
>>> Hi Patrice,
>>>
>>> On Tue, Oct 9, 2018 at 9:41 PM Patrice Chotard <patrice.chotard at st.com> wrote:
>>>>
>>>> Add uclass_foreach_dev_probe() which iterates through
>>>> devices of a given uclass. Devices are probed if necessary
>>>> and are ready to use.
>>>>
>>>> Signed-off-by: Patrice Chotard <patrice.chotard at st.com>
>>>> Reviewed-by: Simon Glass <sjg at chromium.org>
>>>> ---
>>>>
>>>> Changes in v3: None
>>>> Changes in v2: None
>>>>
>>>>  include/dm/uclass.h | 16 ++++++++++++++++
>>>>  1 file changed, 16 insertions(+)
>>>>
>>>> diff --git a/include/dm/uclass.h b/include/dm/uclass.h
>>>> index 6e7c1cd3e8bc..10ccfdce951e 100644
>>>> --- a/include/dm/uclass.h
>>>> +++ b/include/dm/uclass.h
>>>> @@ -376,4 +376,20 @@ int uclass_resolve_seq(struct udevice *dev);
>>>>  #define uclass_foreach_dev_safe(pos, next, uc) \
>>>>         list_for_each_entry_safe(pos, next, &uc->dev_head, uclass_node)
>>>>
>>>> +/**
>>>> + * uclass_foreach_dev_probe() - Helper function to iteration through devices
>>>> + * of given uclass
>>>> + *
>>>> + * This creates a for() loop which works through the available devices in
>>>> + * a uclass in order from start to end. Devices are probed if necessary,
>>>> + * and ready for use.
>>>> + *
>>>> + * @id: Uclass ID
>>>> + * @dev: struct udevice * to hold the current device. Set to NULL when there
>>>> + * are no more devices.
>>>> + */
>>>> +#define uclass_foreach_dev_probe(id, dev)      \
>>>> +       for (uclass_first_device(id, &dev); dev; \
>>>> +            uclass_next_device(&dev))
>>>
>>> Shouldn't we check the return value of uclass_first_device() and
>>> uclass_next_device()?
>>
>> It's not necessary to check the return value of uclass_first_device(id,
>> &dev) because in any error case, dev is NULL, which is the loop output
>> condition. This is only for the first iteration.
>>
> 
> Please see the comment of uclass_first_device().
> 
>  * @devp: Returns pointer to the first device in that uclass if no error
>  * occurred, or NULL if there is no first device, or an error occurred with
>  * that device.
>  * @return 0 if OK (found or not found), other -ve on error
> 
> So it can return error with a valid dev.

I checked the uclass_first_device() implementation and the comment seems
not aligned with what is coded. When uclass_first_device() returns a
valid dev, return value is always 0. (see uclass_get_device_tail()
return value).

In any case uclass_first_device() returns a valid dev with an error.

Simon, Bin do you confirm ?

> 
>> For the other iteration, dev comes from uclass_next_device(&dev),
>> similarly to uclass_first_device(), in any error case dev is NULL.
>>
> 
> Similar please see the comment of uclass_next_device().

I have the same remark regarding uclass_next_device().

Thanks

Patrice

> 
> Regards,
> Bin
>