linux-kernel - Re: [PATCH 11/15] soc: octeontx2: Add Marvell OcteonTX2 CGX driver

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Date:   Tue, 28 Aug 2018 18:39:53 +0530
From:   Sunil Kovvuri <sunil.kovvuri@...il.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     LKML <linux-kernel@...r.kernel.org>, olof@...om.net,
        LAKML <linux-arm-kernel@...ts.infradead.org>,
        linux-soc@...r.kernel.org, Sunil Goutham <sgoutham@...vell.com>
Subject: Re: [PATCH 11/15] soc: octeontx2: Add Marvell OcteonTX2 CGX driver

> > > If this is a regular PCI ethernet driver, why do you put it into driver/soc
> > > rather than drivers/net/ethernet/ ?
> >
> > No, this is not a ethernet driver, as mentioned in the cover letter
> > this driver and AF driver doesn't
> > handle any IO. There will be a separate ethernet driver (will submit
> > that as well in future) which will
> > communicate with these drivers for configuring hardware.
> >
> > The driver in question here is for a serdes controller which handles
> > physical ethernet interfaces.
> > Admin function driver gathers info w.r.t current state of physical
> > ethernet interfaces from this driver
> > and notifies actual ethernet driver about changes, if any.
>
> Ok. Can you describe the structure that the PCI devices appear
> in? It might help to be make the connection between the differnet
> patches to understand how things fit together. In the final
> picture, how many different pci_driver instances do you have,
> and what part are they for?

List of PCI devices are CGX, RVU PF0-PFn SRIOV physical functions
and RVU VF0-VFn SRIOV virtual functions. No of VFs per PF is configurable
and done by low level firmware.

List of PCI driver instances would be CGX driver, RVU PF0 (i.e admin
function) driver,
PF1-PFn either netdev driver or crypto driver, VF0-VFn functionality would be
same as their PF.

The current plan is to have CGX driver, Admin function driver, PF
netdev driver,
VF netdev driver and PF/VF crypto drivers.

>
> Is the idea that an ethernet device driver always attaches to a
> virtual function that gets created by the main driver, and that
> the two drivers share no interfaces on the kernel side, or do
> you have multiple drivers linking to each other?

Ethernet device driver can attach to both physical function and virtual function
whose HW resources are provisioned by admin function driver.

Yes the PF/VF ethernet drivers and these drivers won't share any
kernel interfaces.
Physical ethernet interface is owned by ethernet driver only, this driver just
configures which ethernet driver instance uses which physcial interface.

>
>       Arnd