[PATCH net-next v12 08/18] net: ethernet: mtk_eth_soc: fix 1000Base-X and 2500Base-X modes

[Russell King (Oracle)]

On Tue, Mar 07, 2023 at 03:53:58PM +0000, Daniel Golle wrote:
> After conversion to phylink_pcs the 1000Base-X and 2500Base-X modes
> would work only after `ethtool -s eth1 autoneg off`.
> As ethtool autoneg and the ETHTOOL_LINK_MODE_Autoneg_BIT is supposed
> to control auto-negotiation on the external interface it doesn't make
> much sense to use it to control on-board SGMII auto-negotiation between
> MAC and PHY.
> Set correct values to really only enable SGMII auto-negotiation when
> actually operating in SGMII mode. For 1000Base-X and 2500Base-X mode,
> enable remote-fault detection only if in-band-status is enabled.
> This fixes using 1000Base-X and 2500Base-X SFPs on the BananaPi R3
> board and also makes it possible to use interface-mode-switching PHYs
> operating in either SGMII mode for 10M/100M/1000M or in 2500Base-X for
> 2500M mode on other boards.
> 
> Fixes: 14a44ab0330d ("net: mtk_eth_soc: partially convert to phylink_pcs")
> Signed-off-by: Daniel Golle <daniel at makrotopia.org>

NAK.

There are PHYs out there which operate in SGMII mode but do not
exchange the SGMII 16-bit configuration word. The code implemented
here by me was explicitly to allow such a configuration to work,
which is defined as:

	SGMII *without* mode == inband

An example of this is the Broadcom 84881 PHY which can be found on
SFP modules.

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