linux-kernel - Re: [PATCH 11/15] RDMA/hbl: add habanalabs RDMA driver

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Message-ID: <20240712130856.GB14050@ziepe.ca>
Date: Fri, 12 Jul 2024 10:08:56 -0300
From: Jason Gunthorpe <jgg@...pe.ca>
To: Omer Shpigelman <oshpigelman@...ana.ai>
Cc: Leon Romanovsky <leon@...nel.org>,
	"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
	"ogabbay@...nel.org" <ogabbay@...nel.org>,
	Zvika Yehudai <zyehudai@...ana.ai>
Subject: Re: [PATCH 11/15] RDMA/hbl: add habanalabs RDMA driver

On Fri, Jun 28, 2024 at 10:24:32AM +0000, Omer Shpigelman wrote:

> We need the core driver to access the IB driver (and to the ETH driver as
> well). As you wrote, we can't use exported symbols from our IB driver nor
> rely on function pointers, but what about providing the core driver an ops
> structure? meaning exporting a register function from the core driver that
> should be called by the IB driver during auxiliary device probe.
> Something like:
> 
> int hbl_cn_register_ib_aux_dev(struct auxiliary_device *adev,
> 			       struct hbl_ib_ops *ops)
> {
> ...
> }
> EXPORT_SYMBOL(hbl_cn_register_ib_aux_dev);

Definately do not do some kind of double-register like this.

The auxiliary_device scheme can already be extended to provide ops for
each sub device.

Like

struct habana_driver {
   struct auxiliary_driver base;
   const struct habana_ops *ops;
};

If the ops are justified or not is a different question.

> module reference counter. But we also get the ability to access the IB
> driver from the core driver (to report a HW error for example).

Report a HW error seems reasonable to me

Other driver have used notifier chains for this kind of stuff though.

Jason