[U-Boot] [RFC PATCH] dm: ensure device names are unique

[Stephen Warren]

On 04/26/2016 03:36 PM, Stephen Warren wrote:
> On 04/26/2016 03:30 PM, Stephen Warren wrote:
>> From: Stephen Warren <swarren at nvidia.com>
>>
>> It is possible for HW to contain multiple instances of the same
>> device. In
>> this case, the name passed to device_bind() may not be unique across all
>> devices within its uclass. One example is a system with multiple
>> identical
>> PCI Ethernet devices. Another might be a system with multiple identical
>> I2C GPIO expanders, each connected to a separate I2C bus, yet using the
>> same I2C address on that bus and hence having the same DT node name.
>>
>> Enhance the code to detect this situation, and append a sequence
>> number so
>> the device name to ensure uniqueness.
>>
>> Signed-off-by: Stephen Warren <swarren at nvidia.com>
>> ---
>> Some possible issues with this patch:
>>
>> 1) Doing this in bind() rather than probe() means dev->seq isn't
>> available, so can't be used to generate the unique name. This process
>> should be done during bind() rather than probe() though, since devices
>> can
>> be seen (e.g. by running "dm tree") before they're probed. Perhaps the
>> uclass_resolve_seq() should be called by bind() not probe().
>>
>> 2) uclass_find_device_by_name() needs to look up the uclass pointer again
>> even though device_bind() already knows it.
>>
>> 3) Iterating over the list to find the count of devices in the uclass
>> is a
>> bit annoying. Should the uclass maintain this count so it doesn't need to
>> be re-calculated each time?
>
> 4) This causes "ut dm autobind" to fail. I'll investigate that locally,
> but won't bother reposting until the questions above are considered.

It looks like that's because I need to add "gd->dm_root && " to the 
start of the following condition:

> @@ -62,6 +62,23 @@ int device_bind(struct udevice *parent, const struct driver *drv,
>  	dev->driver = drv;
>  	dev->uclass = uc;
>
> +	if (!uclass_find_device_by_name(uc->uc_drv->id, dev->name, &dev2)) {

... otherwise, the uc_class_get/find() nested inside that end up 
creating a second root uclass.

I can fold that into v2, pending any other comments.