Re: [net-next,PATCH] enetc: Set eMDIO MDC rate to 2.5 MHz only on i.MX95

[Marek Vasut]

On 10/8/26 2:22 AM, Jakub Kicinski wrote:
> On Mon, 05 Oct 2026 15:30:10 +0000 netdev-bot+sashiko@xxxxxxxxxx wrote:
> > > -#define ENETC_EMDIO_CFG \
> > > +#define ENETC_EMDIO_CFG(mdc_div) \
> > >   	(MDIO_CFG_HOLD(2) | \
> > > -	 MDIO_CFG_CLKDIV(66) | \
> > > +	 MDIO_CFG_CLKDIV(mdc_div) | \
> > >   	 MDIO_CFG_NEG)
> >
> > [Severity: High]
> > What divider do the other users of these accessors get?
> >
> > The exported enetc_mdio_read_c22(), enetc_mdio_write_c22(),
> > enetc_mdio_read_c45() and enetc_mdio_write_c45() are shared with several
> > bus constructors. Only enetc_pci_mdio_probe() sets mdc_div.
> >
> > These constructors install the same accessors but set only hw and
> > mdio_base:
> >
> >    enetc_mdio_probe() in enetc_pf_common.c (PF external MDIO, LS1028A
> >    and ENETC4)
> >    enetc_imdio_create() in enetc_pf_common.c (internal Lynx PCS MDIO)
> >    netc_port_create_emdio_bus() in drivers/net/dsa/netc/netc_main.c
> >    vsc9959_mdio_bus_alloc() in drivers/net/dsa/ocelot/felix_vsc9959.c
> >
> > For example:
> >
> > enetc_pf_common.c:enetc_mdio_probe() {
> >      ...
> >      bus = devm_mdiobus_alloc_size(dev, sizeof(*mdio_priv));
> >      ...
> >      mdio_priv->hw = &pf->si->hw;
> >      if (is_enetc_rev1(pf->si))
> >          mdio_priv->mdio_base = ENETC_EMDIO_BASE;
> >      else
> >          mdio_priv->mdio_base = ENETC4_EMDIO_BASE;
> >      ...
> > }
> >
> > mdiobus_alloc_size() allocates the priv area with kzalloc(), so mdc_div
> > stays 0. MDIO_CFG_CLKDIV(x) is ((((x) >> 1) & 0xff) << 8).
> >
> > As a result, every C22/C45 transaction on these buses would write a zero
> > clock divider into ENETC_MDIO_CFG. Before 587acb86d646 the value was 258,
> > and after it the value was 66.
>
> Looks legit.

Let me fill the default into Ocelot and enetc_pf_common.c