Re: [PATCH v3 05/13] i2c: acpi: Return error pointers from i2c_acpi_new_device()

Andy Shevchenko
2018-11-27T19:27:46Z

On Tue, Nov 27, 2018 at 05:14:06PM +0100, Hans de Goede wrote:
> On 27-11-18 16:37, Andy Shevchenko wrote:
> > The caller would like to know the reason why the i2c_acpi_new_device() fails.
> > For example, if adapter is not available, it might be in the future and we
> > would like to re-probe the clients again. But at the same time we would like to
> > bail out if the error seems unrecoverable, such as invalid argument supplied.
> > To achieve this, return error pointer in some cases.

> > acpi_dev_free_resource_list(&resource_list);
> > - if (ret < 0 || !info->addr)
> > - return NULL;
> > + if (!info->addr)
> > + return ERR_PTR(-EADDRNOTAVAIL);
> > adapter = i2c_acpi_find_adapter_by_handle(lookup.adapter_handle);
> > if (!adapter)
> > - return NULL;
> > + return ERR_PTR(-ENODEV);

> Why not simply return -EPROBE_DEFER here (and simplify the callers a lot).

> This is the only case where we really want to defer.

> > + client = i2c_new_device(adapter, info);
> > + if (!client)
> > + return ERR_PTR(-ENODEV);
>
> If you look at i2c_new_device, it can fail because it is
> out of memory, the i2c slave address is invalid, or
> their already is an i2c slave with the same address,
> iow if this were to return an ERR_PTR itself, this
> would return -ENOMEM, -EINVAL or -EBUSY and never
> -EPROBE_DEFER.

It would change the behaviour.

In any case, it's only two users and both written by you, so, just to be sure
you aware of this change and bless it.

--
With Best Regards,
Andy Shevchenko