On Mon, Jul 20, 2020 at 03:50:57PM +0000, Ioana Ciornei wrote:
> On 6/30/20 5:29 PM, Russell King wrote:
> > Add a way for MAC PCS to have private data while keeping independence
> > from struct phylink_config, which is used for the MAC itself. We need
> > this independence as we will have stand-alone code for PCS that is
> > independent of the MAC. Introduce struct phylink_pcs, which is
> > designed to be embedded in a driver private data structure.
> >
> > This structure does not include a mdio_device as there are PCS
> > implementations such as the Marvell DSA and network drivers where this
> > is not necessary.
> >
> > Signed-off-by: Russell King <rmk+ker...@armlinux.org.uk>
>
> Reviewed-by: Ioana Ciornei <ioana.cior...@nxp.com>
>
> I integrated and used the phylink_pcs structure into the Lynx PCS just
> to see how everything fits. Pasting below the main parts so that we can
> catch early any possible different opinions on how to integrate this:
>
> The basic Lynx structure looks like below and the main idea is just to
> encapsulate the phylink_pcs structure and the mdio device (which in some
> other cases might not be needed).
>
> struct lynx_pcs {
> struct phylink_pcs pcs;
> struct mdio_device *mdio;
> phy_interface_t interface;
> };
>
> The lynx_pcs structure is requested by the MAC driver with:
>
> struct lynx_pcs *lynx_pcs_create(struct mdio_device *mdio)
> {
> (...)
> lynx_pcs->mdio = mdio;
> lynx_pcs->pcs.ops = &lynx_pcs_phylink_ops;
> lynx_pcs->pcs.poll = true;
>
> return lynx_pcs;
> }
>
> And then passed to phylink with something like:
>
> phylink_set_pcs(pl, &lynx_pcs->pcs);
>
>
> For DSA it's a bit less straightforward because the .setup() callback
> from the dsa_switch_ops is run before any phylink structure has been
> created internally. For this, a new DSA helper can be created that just
> stores the phylink_pcs structure per port:
>
> void dsa_port_phylink_set_pcs(struct dsa_switch *ds, int port,
> struct phylink_pcs *pcs)
> {
> struct dsa_port *dp = dsa_to_port(ds, port);
>
> dp->pcs = pcs; but I do
> }
>
> and at the appropriate time, from dsa_slave_setup, it can really install
> the phylink_pcs with phylink_set_pcs.
> The other option would be to add a new dsa_switch ops that requests the
> phylink_pcs for a specific port - something like phylink_get_pcs.
It is entirely possible to set the PCS in the mac_prepare() or
mac_config() callbacks - but DSA doesn't yet support the mac_prepare()
callback (because it needs to be propagated through the DSA way of
doing things.)
An example of this can be found at:
http://git.armlinux.org.uk/cgit/linux-arm.git/commit/?h=mcbin&id=593d56ef8c7f7d395626752f6810210471a5f5c1
where we choose between the XLGMAC and GMAC pcs_ops structures
depending on the interface mode we are configuring for. Note that
this is one of the devices that the PCS does not appear as a
distinctly separate entity in the register set, at least in the
GMAC side of things.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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