Re: [PATCH RFC net-next v2 17/17] net: stmmac: pcs: Drop the _SHIFT macros

Serge Semin
2024-07-04T13:19:52Z

On Fri, Jun 28, 2024 at 03:42:41PM +0100, Russell King (Oracle) wrote:
> On Mon, Jun 24, 2024 at 04:26:34PM +0300, Serge Semin wrote:
> > The PCS_ANE_PSE_SHIFT and PCS_ANE_RFE_SHIFT are unused anyway. Moreover
> > PCS_ANE_PSE and PCS_ANE_RFE are the respective field masks. So the
> > FIELD_GET()/FIELD_SET() macro-functions can be used to get/set the fields
> > content. Drop the _SHIFT macros for good then.
> >
> > Signed-off-by: Serge Semin <fancer.lancer@gmail.com>
> > ---
> > drivers/net/ethernet/stmicro/stmmac/stmmac_pcs.h | 2 --
> > 1 file changed, 2 deletions(-)
> >
> > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_pcs.h b/drivers/net/ethernet/stmicro/stmmac/stmmac_pcs.h
> > index a17e5b37c411..0f15c9898788 100644
> > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_pcs.h
> > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_pcs.h
> > @@ -43,9 +43,7 @@
> > #define PCS_ANE_FD BIT(5) /* AN Full-duplex flag */
> > #define PCS_ANE_HD BIT(6) /* AN Half-duplex flag */
> > #define PCS_ANE_PSE GENMASK(8, 7) /* AN Pause Encoding */
> > -#define PCS_ANE_PSE_SHIFT 7
> > #define PCS_ANE_RFE GENMASK(13, 12) /* AN Remote Fault Encoding */
> > -#define PCS_ANE_RFE_SHIFT 12
> > #define PCS_ANE_ACK BIT(14) /* AN Base-page acknowledge */
>

> I would actually like to see all these go away.
>
> PCS_ANE_FD == LPA_1000XFULL
> PCS_ANE_HD == LPA_1000XHALF
> PCS_ANE_PSE == LPA_1000XPAUSE and LPA_1000XPAUSE_ASYM
> PCS_ANE_RFE == LPA_RESV and LPA_RFAULT
> PCS_ANE_ACK == LPA_LPACK

Great! It will be even better.

>
> Isn't it rather weird that the field layout matches 802.3z aka
> 1000base-X and not SGMII? This layout would not make sense for Cisco
> SGMII as it loses the speed information conveyed by the Cisco SGMII
> control word.
>
> This isn't a case of the manufacturer using "SGMII" to mean a serial
> gigabit media independent interface that supports 1000base-X
> (PHY_INTERFACE_MODE_1000BASEX) rather than Cisco SGMII
> (PHY_INTERFACE_MODE_SGMII) ?

It's not that weird. The only CSRs available and functional for SGMII
PCS are PCS_AN_CTRL and PCS_AN_STATUS (plus PCS_SRGMII_CSR where the
PCS exposes the link status, aka Cisco SGMII tx_config_reg[15:0] with
the vendor-specific layout). Registers from PCS_ANE_ADV up to PCS_TBI_EXT
exist for TBI and RTBI PCS only. Since TBI is defined in the IEEE
802.3z C36 I guess that's why the layout matches to what is described
in IEEE 802.3z C37.

-Serge(y)

>
> --
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