[openib-general] Proposed device enumeration & async event APIs

[Grant Grundler]

On Mon, Sep 13, 2004 at 12:38:53PM -0700, Roland Dreier wrote:
>     Grant> This sounds no different than say tulip driver which might
>     Grant> claim multiple 100BT cards below different PCI Busses.
> 
> The difference is that not only can only a client have multiple
> devices, but also a device can have multiple clients.  So PCI devices
> can get away with a single slot to track driver context.

I'm suggesting there should be an equivalent 1:1 for each IPoIB instance.
ie each IPoIB client is dealing with a virtual NIC.

>     Grant> I expect each client to have some data structure to track
>     Grant> state info and each "parent" device must know something
>     Grant> about it. Ie when the parent device goes away, each related
>     Grant> client instance must be notified.  Or is that not true
>     Grant> either?
> 
> There's a list of devices and a list of clients.  When a device is
> added or removed, every client on the list gets a callback (ib_device
> is sort of like class_device and ib_client is sort of like
> class_interface in the driver model).

We don't know which client instances are bound to a particular device?

> 
>     Grant> I agree we can't avoid the dynamic allocation.  But we can
>     Grant> choose when it happens.  I'm just questioning if it really
>     Grant> needs to happen in get/set private data.  I'm thinking it
>     Grant> should happen during some part of the initialization and
>     Grant> removal of specific instances of a client.
> 
> Sure, we could allocate client context before we call the client back
> for a device add (and just not even call the client back if the
> allocation failed).  Does that seem better?

Yeah - I think so. It would match the analogy to PCI support alot better.
And the IB support interfaces would in turn behave like those for PCI
as well - and not just look like them.

But I don't want to turn the IB world upside down to make that work.
If if doesn't make sense, do it the way you proposed originally.

thanks,
grant