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

[Bin Meng]

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.

> 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().

Regards,
Bin