netdev - Re: [RFC 01/20] ice: Initialize and register multi-function device to provide RDMA

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Date:   Wed, 23 Oct 2019 14:44:48 -0300
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     "Ertman, David M" <david.m.ertman@...el.com>
Cc:     "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "Nguyen, Anthony L" <anthony.l.nguyen@...el.com>,
        "Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>,
        "dledford@...hat.com" <dledford@...hat.com>
Subject: Re: [RFC 01/20] ice: Initialize and register multi-function device
 to provide RDMA

On Fri, Sep 27, 2019 at 06:03:51PM +0000, Ertman, David M wrote:
> > From: gregkh@...uxfoundation.org [mailto:gregkh@...uxfoundation.org]
> > Sent: Thursday, September 26, 2019 10:13 PM
> > To: Nguyen, Anthony L <anthony.l.nguyen@...el.com>
> > Cc: Kirsher, Jeffrey T <jeffrey.t.kirsher@...el.com>; jgg@...lanox.com;
> > netdev@...r.kernel.org; linux-rdma@...r.kernel.org; dledford@...hat.com;
> > Ertman, David M <david.m.ertman@...el.com>
> > Subject: Re: [RFC 01/20] ice: Initialize and register multi-function device to
> > provide RDMA
> > 
> > On Thu, Sep 26, 2019 at 11:39:22PM +0000, Nguyen, Anthony L wrote:
> > > On Thu, 2019-09-26 at 20:05 +0200, Greg KH wrote:
> > > > On Thu, Sep 26, 2019 at 09:45:00AM -0700, Jeff Kirsher wrote:
> > > > > From: Tony Nguyen <anthony.l.nguyen@...el.com>
> > > > >
> > > > > The RDMA block does not advertise on the PCI bus or any other bus.
> > > >
> > > > Huh?  How do you "know" where it is then?  Isn't is usually assigned
> > > > to a PCI device?
> > >
> > > The RDMA block does not have its own PCI function so it must register
> > > and interact with the ice driver.
> > 
> > So the "ice driver" is the real thing controlling the pci device?  How does it
> > "know" about the RDMA block?
> > 
> > thanks,
> > 
> > greg k-h
> 
> The ICE driver loads and registers to control the PCI device.  It then
> creates an MFD device with the name 'ice_rdma'. The device data provided to
> the MFD subsystem by the ICE driver is the struct iidc_peer_dev which
> contains all of the relevant information that the IRDMA peer will need
> to access this PF's IIDC API callbacks
> 
> The IRDMA driver loads as a software only driver, and then registers a MFD
> function driver that takes ownership of MFD devices named 'ice_rdma'.
> This causes the platform bus to perform a matching between ICE's MFD device
> and IRDMA's driver.  Then the patform bus will call the IRDMA's IIDC probe
> function.  This probe provides the device data to IRDMA.

Did any resolution happen here? Dave, do you know what to do to get
Greg's approval?

Jason