[U-Boot] [RFC PATCH v3 01/14] dm: core: Allow seq numbers to be resolved before probe

[Joe Hershberger]

Hi Simon,

On Tue, Feb 10, 2015 at 10:39 PM, Simon Glass <sjg at chromium.org> wrote:
>
> Hi Joe,
>
> On 10 February 2015 at 18:30, Joe Hershberger <joe.hershberger at ni.com>
wrote:
> > Before this patch, if the sequence numbers were resolved before probe,
> > this code would insist on defining new non-conflicting-with-itself seq
> > numbers. Now any "non -1" seq number is accepted as already resolved.
>
> Can you explain what problem this solves? At present, when probing a
> device, ->seq must be -1 (sort-of by definition since it doesn't exist
> as an active device in the uclass).

Please look at eth_post_bind() in patch 07/14.  The Ethernet devices need
to write their hardware addresses to the registers in bind (since it needs
to happen regardless of the device being used so that Linux will see the
MAC address).  As such, the sequence number is needed to look up the
ethaddr. In order to avoid probing all the devices to get the seq number
resolved, I resolve it in post_bind to avoid the rest of the overhead (thus
no longer probing in post_bind, which was one of the issues previously).
Then when probe comes along, the seq is already resolved.  That's why this
patch is needed.

Thanks,
-Joe